Only create drawables for storyboard elements that will be visible.

osu.Game/Storyboards/Drawables/DrawableStoryboardAnimation.cs

@@ -14,9 +14,6 @@ namespace osu.Game.Storyboards.Drawables
     {
         public StoryboardAnimation Animation { get; private set; }
 
-        protected override bool ShouldBeAlive => Animation.HasCommands && base.ShouldBeAlive;
-        public override bool RemoveWhenNotAlive => !Animation.HasCommands || base.RemoveWhenNotAlive;
-
         public bool FlipH { get; set; }
         public bool FlipV { get; set; }
 
@@ -59,11 +56,8 @@ namespace osu.Game.Storyboards.Drawables
             Position = animation.InitialPosition;
             Repeat = animation.LoopType == AnimationLoopType.LoopForever;
 
-            if (animation.HasCommands)
-            {
-                LifetimeStart = animation.StartTime;
-                LifetimeEnd = animation.EndTime;
-            }
+            LifetimeStart = animation.StartTime;
+            LifetimeEnd = animation.EndTime;
         }
 
         [BackgroundDependencyLoader]

osu.Game/Storyboards/Drawables/DrawableStoryboardLayer.cs

@@ -28,9 +28,8 @@ namespace osu.Game.Storyboards.Drawables
         {
             foreach (var element in Layer.Elements)
             {
-                var drawable = element.CreateDrawable();
-                if (drawable != null)
-                    Add(drawable);
+                if (element.IsDrawable)
+                    Add(element.CreateDrawable());
             }
         }
     }

osu.Game/Storyboards/Drawables/DrawableStoryboardSprite.cs

@@ -14,9 +14,6 @@ namespace osu.Game.Storyboards.Drawables
     {
         public StoryboardSprite Sprite { get; private set; }
 
-        protected override bool ShouldBeAlive => Sprite.HasCommands && base.ShouldBeAlive;
-        public override bool RemoveWhenNotAlive => !Sprite.HasCommands || base.RemoveWhenNotAlive;
-
         public bool FlipH { get; set; }
         public bool FlipV { get; set; }
 
@@ -58,11 +55,8 @@ namespace osu.Game.Storyboards.Drawables
             Origin = sprite.Origin;
             Position = sprite.InitialPosition;
 
-            if (sprite.HasCommands)
-            {
-                LifetimeStart = sprite.StartTime;
-                LifetimeEnd = sprite.EndTime;
-            }
+            LifetimeStart = sprite.StartTime;
+            LifetimeEnd = sprite.EndTime;
         }
 
         [BackgroundDependencyLoader]

osu.Game/Storyboards/StoryboardSample.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
 using osu.Framework.Graphics;
+using System;
 
 namespace osu.Game.Storyboards
 {
@@ -21,6 +22,8 @@ namespace osu.Game.Storyboards
         }
 
         public Drawable CreateDrawable()
-            => null;
+        {
+            throw new InvalidOperationException();
+        }
     }
 }