sizzlinkola Even without splicing, appropriate mesh vertex settings allow you to animate an image to some extent. For example, the nose and mouth of facial meshes in the following blog post are not separated (The eyeballs are separated from the face meshes, though.):
http://esotericsoftware.com/blog/A-taxonomy-of-meshes#Faces
Whether you should separate the layers depends on whether they will overlap each other in animations. For example, dynamic movements such as the animated flapping of a bird's wings shown in the "Simple meshes serving a complex purpose" section of that blog post cannot be achieved without separating the body and wing layers.
It is indeed difficult and troublesome to separate everything perfectly at once, so it may be a good idea to adopt a workflow in which animate the image as is first, and separate only the portions that are judged to be necessary to be separated during the animating process.
