diff --git a/source/blender/editors/space_outliner/outliner_tree.cc b/source/blender/editors/space_outliner/outliner_tree.cc
index 04312b9e6c0..5226c09bf41 100644
--- a/source/blender/editors/space_outliner/outliner_tree.cc
+++ b/source/blender/editors/space_outliner/outliner_tree.cc
@@ -324,7 +324,7 @@ TreeElement *outliner_add_element(SpaceOutliner *space_outliner,
   if (!expand) {
     /* Pass */
   }
-  else if (te->abstract_element && te->abstract_element->isExpandValid()) {
+  else if (te->abstract_element) {
     tree_element_expand(*te->abstract_element, *space_outliner);
   }
   else if (ELEM(type,
diff --git a/source/blender/editors/space_outliner/tree/tree_element.hh b/source/blender/editors/space_outliner/tree/tree_element.hh
index 0ddaba609dc..eafe6011c3a 100644
--- a/source/blender/editors/space_outliner/tree/tree_element.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element.hh
@@ -48,15 +48,6 @@ class AbstractTreeElement {
     return true;
   }
 
-  /**
-   * Just while transitioning to the new tree-element design: Some types are only partially ported,
-   * and the expanding isn't done yet.
-   */
-  virtual bool isExpandValid() const
-  {
-    return true;
-  }
-
   TreeElement &getLegacyElement()
   {
     return legacy_te_;
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id.hh b/source/blender/editors/space_outliner/tree/tree_element_id.hh
index cac3556914e..89be302aa16 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element_id.hh
@@ -28,14 +28,6 @@ class TreeElementID : public AbstractTreeElement {
 
   bool expandPoll(const SpaceOutliner &) const override;
 
-  /**
-   * Expanding not implemented for all types yet. Once it is, this can be set to true or
-   * `AbstractTreeElement::expandValid()` can be removed altogether.
-   */
-  bool isExpandValid() const override
-  {
-    return true;
-  }
   void expand(SpaceOutliner &) const override;
 
   ID &get_ID()
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_armature.cc b/source/blender/editors/space_outliner/tree/tree_element_id_armature.cc
index a7fa4028e79..74057845346 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_armature.cc
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_armature.cc
@@ -48,11 +48,6 @@ void TreeElementIDArmature::expand(SpaceOutliner &space_outliner) const
   }
 }
 
-bool TreeElementIDArmature::isExpandValid() const
-{
-  return true;
-}
-
 void TreeElementIDArmature::expandEditBones(SpaceOutliner &space_outiner) const
 {
   int a = 0;
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_armature.hh b/source/blender/editors/space_outliner/tree/tree_element_id_armature.hh
index 479755a95cd..6b156a954c9 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_armature.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_armature.hh
@@ -23,7 +23,6 @@ class TreeElementIDArmature final : public TreeElementID {
   TreeElementIDArmature(TreeElement &legacy_te, bArmature &arm);
 
   void expand(SpaceOutliner &) const override;
-  bool isExpandValid() const override;
 
  private:
   void expandEditBones(SpaceOutliner &) const;
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_collection.cc b/source/blender/editors/space_outliner/tree/tree_element_id_collection.cc
index 3e792a1b4fc..b338d366d95 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_collection.cc
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_collection.cc
@@ -21,11 +21,6 @@ TreeElementIDCollection::TreeElementIDCollection(TreeElement &legacy_te, Collect
 {
 }
 
-bool TreeElementIDCollection::isExpandValid() const
-{
-  return true;
-}
-
 void TreeElementIDCollection::expand(SpaceOutliner &space_outliner) const
 {
   /* Don't expand for instances, creates too many elements. */
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_collection.hh b/source/blender/editors/space_outliner/tree/tree_element_id_collection.hh
index 7bddcc63c27..425b8ffcc63 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_collection.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_collection.hh
@@ -19,7 +19,6 @@ class TreeElementIDCollection final : public TreeElementID {
   TreeElementIDCollection(TreeElement &legacy_te, Collection &collection);
 
   void expand(SpaceOutliner &) const override;
-  bool isExpandValid() const override;
 };
 
 }  // namespace blender::ed::outliner
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_curve.cc b/source/blender/editors/space_outliner/tree/tree_element_id_curve.cc
index fa57c332080..0acbfed22ea 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_curve.cc
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_curve.cc
@@ -21,11 +21,6 @@ TreeElementIDCurve::TreeElementIDCurve(TreeElement &legacy_te, Curve &curve)
 {
 }
 
-bool TreeElementIDCurve::isExpandValid() const
-{
-  return true;
-}
-
 void TreeElementIDCurve::expand(SpaceOutliner &space_outliner) const
 {
   expand_animation_data(space_outliner, curve_.adt);
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_curve.hh b/source/blender/editors/space_outliner/tree/tree_element_id_curve.hh
index 0d580b17987..2a4da3bf9ef 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_curve.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_curve.hh
@@ -19,7 +19,6 @@ class TreeElementIDCurve final : public TreeElementID {
   TreeElementIDCurve(TreeElement &legacy_te, Curve &curve);
 
   void expand(SpaceOutliner &) const override;
-  bool isExpandValid() const override;
 
  private:
   void expandMaterials(SpaceOutliner &) const;
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_gpencil_legacy.cc b/source/blender/editors/space_outliner/tree/tree_element_id_gpencil_legacy.cc
index ce423cf4514..1e2bf4a9212 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_gpencil_legacy.cc
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_gpencil_legacy.cc
@@ -31,11 +31,6 @@ void TreeElementIDGPLegacy::expand(SpaceOutliner &space_outliner) const
   expandLayers(space_outliner);
 }
 
-bool TreeElementIDGPLegacy::isExpandValid() const
-{
-  return true;
-}
-
 void TreeElementIDGPLegacy::expandLayers(SpaceOutliner &space_outliner) const
 {
   int index = 0;
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_gpencil_legacy.hh b/source/blender/editors/space_outliner/tree/tree_element_id_gpencil_legacy.hh
index d284e1f3b27..7ccd90c1035 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_gpencil_legacy.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_gpencil_legacy.hh
@@ -19,7 +19,6 @@ class TreeElementIDGPLegacy final : public TreeElementID {
   TreeElementIDGPLegacy(TreeElement &legacy_te, bGPdata &gpd);
 
   void expand(SpaceOutliner &) const override;
-  bool isExpandValid() const override;
 
  private:
   void expandLayers(SpaceOutliner &) const;
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_library.cc b/source/blender/editors/space_outliner/tree/tree_element_id_library.cc
index 59ebc5313f9..e2810227672 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_library.cc
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_library.cc
@@ -23,11 +23,6 @@ TreeElementIDLibrary::TreeElementIDLibrary(TreeElement &legacy_te, Library &libr
   legacy_te.name = library.filepath;
 }
 
-bool TreeElementIDLibrary::isExpandValid() const
-{
-  return true;
-}
-
 StringRefNull TreeElementIDLibrary::getWarning() const
 {
   Library &library = reinterpret_cast<Library &>(id_);
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_library.hh b/source/blender/editors/space_outliner/tree/tree_element_id_library.hh
index fdb2622b76d..1ddcd585bc7 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_library.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_library.hh
@@ -18,8 +18,6 @@ class TreeElementIDLibrary final : public TreeElementID {
  public:
   TreeElementIDLibrary(TreeElement &legacy_te, Library &library);
 
-  bool isExpandValid() const override;
-
   blender::StringRefNull getWarning() const override;
 };
 
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_linestyle.cc b/source/blender/editors/space_outliner/tree/tree_element_id_linestyle.cc
index f5b3fbe80eb..8da3994719a 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_linestyle.cc
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_linestyle.cc
@@ -31,11 +31,6 @@ void TreeElementIDLineStyle::expand(SpaceOutliner &space_outliner) const
   expandTextures(space_outliner);
 }
 
-bool TreeElementIDLineStyle::isExpandValid() const
-{
-  return true;
-}
-
 void TreeElementIDLineStyle::expandTextures(SpaceOutliner &space_outliner) const
 {
   for (int a = 0; a < MAX_MTEX; a++) {
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_linestyle.hh b/source/blender/editors/space_outliner/tree/tree_element_id_linestyle.hh
index 5c4b4009ef5..9b6dbf8bc30 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_linestyle.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_linestyle.hh
@@ -21,7 +21,6 @@ class TreeElementIDLineStyle final : public TreeElementID {
   TreeElementIDLineStyle(TreeElement &legacy_te, FreestyleLineStyle &linestyle);
 
   void expand(SpaceOutliner &) const override;
-  bool isExpandValid() const override;
 
  private:
   void expandTextures(SpaceOutliner &) const;
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_mesh.cc b/source/blender/editors/space_outliner/tree/tree_element_id_mesh.cc
index fc61a2b3b5a..b2fa02f4337 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_mesh.cc
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_mesh.cc
@@ -21,11 +21,6 @@ TreeElementIDMesh::TreeElementIDMesh(TreeElement &legacy_te_, Mesh &mesh)
 {
 }
 
-bool TreeElementIDMesh::isExpandValid() const
-{
-  return true;
-}
-
 void TreeElementIDMesh::expand(SpaceOutliner &space_outliner) const
 {
   expand_animation_data(space_outliner, mesh_.adt);
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_mesh.hh b/source/blender/editors/space_outliner/tree/tree_element_id_mesh.hh
index a07ec93815d..59bf1767cfa 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_mesh.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_mesh.hh
@@ -19,7 +19,6 @@ class TreeElementIDMesh final : public TreeElementID {
   TreeElementIDMesh(TreeElement &legacy_te_, Mesh &mesh);
 
   void expand(SpaceOutliner &) const override;
-  bool isExpandValid() const override;
 
  private:
   void expandKey(SpaceOutliner &) const;
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_metaball.cc b/source/blender/editors/space_outliner/tree/tree_element_id_metaball.cc
index aba6d39e762..aeb3104e396 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_metaball.cc
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_metaball.cc
@@ -21,11 +21,6 @@ TreeElementIDMetaBall::TreeElementIDMetaBall(TreeElement &legacy_te, MetaBall &m
 {
 }
 
-bool TreeElementIDMetaBall::isExpandValid() const
-{
-  return true;
-}
-
 void TreeElementIDMetaBall::expand(SpaceOutliner &space_outliner) const
 {
   expand_animation_data(space_outliner, metaball_.adt);
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_metaball.hh b/source/blender/editors/space_outliner/tree/tree_element_id_metaball.hh
index 192ee83fbbf..d2b17e4c4e4 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_metaball.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_metaball.hh
@@ -21,7 +21,6 @@ class TreeElementIDMetaBall final : public TreeElementID {
   TreeElementIDMetaBall(TreeElement &legacy_te, MetaBall &metaball);
 
   void expand(SpaceOutliner &) const override;
-  bool isExpandValid() const override;
 
  private:
   void expandMaterials(SpaceOutliner &) const;
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_object.cc b/source/blender/editors/space_outliner/tree/tree_element_id_object.cc
index c311f14cf98..37d94a1ab72 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_object.cc
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_object.cc
@@ -51,11 +51,6 @@ void TreeElementIDObject::expand(SpaceOutliner &space_outliner) const
   expandDuplicatedGroup(space_outliner);
 }
 
-bool TreeElementIDObject::isExpandValid() const
-{
-  return true;
-}
-
 void TreeElementIDObject::expandData(SpaceOutliner &space_outliner) const
 {
   outliner_add_element(
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_object.hh b/source/blender/editors/space_outliner/tree/tree_element_id_object.hh
index 553c45feb8a..7e5db814507 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_object.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_object.hh
@@ -19,7 +19,6 @@ class TreeElementIDObject final : public TreeElementID {
   TreeElementIDObject(TreeElement &legacy_te, Object &object);
 
   void expand(SpaceOutliner &) const override;
-  bool isExpandValid() const override;
 
  private:
   void expandData(SpaceOutliner &) const;
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_scene.cc b/source/blender/editors/space_outliner/tree/tree_element_id_scene.cc
index 5f429266281..203fe43bbd5 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_scene.cc
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_scene.cc
@@ -21,11 +21,6 @@ TreeElementIDScene::TreeElementIDScene(TreeElement &legacy_te, Scene &scene)
 {
 }
 
-bool TreeElementIDScene::isExpandValid() const
-{
-  return true;
-}
-
 void TreeElementIDScene::expand(SpaceOutliner &space_outliner) const
 {
   expandViewLayers(space_outliner);
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_scene.hh b/source/blender/editors/space_outliner/tree/tree_element_id_scene.hh
index 55f5eb91dbc..6a05ee52134 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_scene.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_scene.hh
@@ -19,7 +19,6 @@ class TreeElementIDScene final : public TreeElementID {
   TreeElementIDScene(TreeElement &legacy_te, Scene &scene);
 
   void expand(SpaceOutliner &) const override;
-  bool isExpandValid() const override;
 
  private:
   void expandViewLayers(SpaceOutliner &) const;
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_texture.cc b/source/blender/editors/space_outliner/tree/tree_element_id_texture.cc
index 913372de309..bebdcade921 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_texture.cc
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_texture.cc
@@ -21,11 +21,6 @@ TreeElementIDTexture::TreeElementIDTexture(TreeElement &legacy_te, Tex &texture)
 {
 }
 
-bool TreeElementIDTexture::isExpandValid() const
-{
-  return true;
-}
-
 void TreeElementIDTexture::expand(SpaceOutliner &space_outliner) const
 {
   expand_animation_data(space_outliner, texture_.adt);
diff --git a/source/blender/editors/space_outliner/tree/tree_element_id_texture.hh b/source/blender/editors/space_outliner/tree/tree_element_id_texture.hh
index 1251c1f05d4..15a96006f4c 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_id_texture.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element_id_texture.hh
@@ -19,7 +19,6 @@ class TreeElementIDTexture final : public TreeElementID {
   TreeElementIDTexture(TreeElement &legacy_te, Tex &texture);
 
   void expand(SpaceOutliner &) const override;
-  bool isExpandValid() const override;
 
  private:
   void expandImage(SpaceOutliner &) const;
diff --git a/source/blender/editors/space_outliner/tree/tree_element_rna.cc b/source/blender/editors/space_outliner/tree/tree_element_rna.cc
index 24e10383c22..f4f07b5867f 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_rna.cc
+++ b/source/blender/editors/space_outliner/tree/tree_element_rna.cc
@@ -44,11 +44,6 @@ TreeElementRNACommon::TreeElementRNACommon(TreeElement &legacy_te, PointerRNA &r
   }
 }
 
-bool TreeElementRNACommon::isExpandValid() const
-{
-  return true;
-}
-
 bool TreeElementRNACommon::isRNAValid() const
 {
   return rna_ptr_.data != nullptr;
diff --git a/source/blender/editors/space_outliner/tree/tree_element_rna.hh b/source/blender/editors/space_outliner/tree/tree_element_rna.hh
index feeb89a35e9..b9471f0e2dd 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_rna.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element_rna.hh
@@ -28,7 +28,6 @@ class TreeElementRNACommon : public AbstractTreeElement {
 
  public:
   TreeElementRNACommon(TreeElement &legacy_te, PointerRNA &rna_ptr);
-  bool isExpandValid() const override;
   bool expandPoll(const SpaceOutliner &) const override;
 
   const PointerRNA &getPointerRNA() const;