But You see, that's where I feel there is not much more than a cosmetic difference.
Let's say we have a separate event sheet for our animation system.
Then for every new level (new layout), we include it into the new layout's event sheet. What we then see is a small line, saying "Inlcude Event Sheet: ..."
Now, what if I just had all the code from the animation event sheet inside a group?
Then what we would have is, instead of "Include Event Sheet: ...", a line saying the name of the group "Animation System", which we could expand.
Now for every new level, we just copy the layout with it's event sheet, or include that layout's event sheet in the new layout, and delete all the parts not fitting the new level, and add the parts specific to that new level.