A pro would use a layer for each main part, with additional layers for some of the shadows and effects I think. But I don't think every shadow needs it's own layer. Makes it too hard to handle everything. Just. 1 layer is hard too, since shading done to egdes of objects can easily bleed over to others.
My last couple heads never passed 20 actual layers. (had some extra for scratched ideas and stuff) and those heads had far more different objects.
Plus, you can put more than one element in a layer as long as they are similar. Or like if they don't touch. Works out for me pretty well and reduces time spent clicking through each layer to figure out where I drew what.
I really hope prices rise with the 512 textures. They are 16x more pixels to draw. This doesn't matter for more vector styled textures, but for those of us who draw it by hand, it can easily be more than 4x the work vs 128.
This was 512 right? I mean, if you don't make more by making 512, might as well work in 128. :/