well how did you do that??? you can’t distribute bones of ONE armature across different layers. you can use multiple armatures on multiple objects, but there’s no way known (to me) to deform ONE mesh with MULTIPLE armatures.
however separating armatures makes sense in some situations. two years ago i used a rig where both hands and the head were separate object driven by their own armature. this worked because the character weared clothes, so no unnatural seams were seen. i had an additional armature which was the controller for all other armatures (mainly IK- and pos/rot-constraints). it was on a different layer, and i experienced some lag in update. but that was back in the 225 era, those issues are solved now.
IMO thesea are the most important things for rigging:
- as few bones as possible
- proper weighting
- good and clever controls (IK etc) - e.g. you don’t need an IK target for every vertebra, nor for knees or hips. in most cases parenting the hand-IK-constraints to the upper body is also a good idea, so you don’t have to worry abt. your arms lagging behind the character as he walks forward
- as few control-objects for the animator as possible
try to find methods for animating that make your work easy while animating. if you plan to use facial animation, use RVK’s rather then bones. if you have longer animations with motions that can be reused (like walk-cycles or hand-gestures) use the NLA for that
also always have a lok at the developer forums on blender.org, new features come every month. the most spectacular ones were the stretch-to constraint (making bones stretch automatically to reach a target), the hooks-feature (great helper for mesh deformation) and the path-deform (hello squiddy). there are still some issues when using them in combination, but it’s as always a matter of time till they work perfectly.