In reference to the layering it is great that grouping is used ie. numerical grouping, however if you use a system it should be carried thru I know that there are layer names that have no number associated ie. scene etc, how ever this can easily be placed under a number "x=all scenes" this way all your relevant info is grouped together same as for the item grouping this should all share the same convention which currently has GROUP as the main key, so it is easier to control. With my current practice I tend to have the grouping appear at the top of the layer list as this is the most used when control groups of information when modeling. I have requested a current layer setup to better understand the various relationships etc and the complexity.