I have a large feature class containing many thousands of polygons. For several reasons, at least part of the time in our development/deployment process, it lives in a file GDB.
It is part of a map service that we publish where there are different layers based on multiple (4-6) thematic versions of this same feature class (rendered, filtered, and labeled based on different attribute values).
Basically, I've been adding the feature class to the map, renaming the layer, setting the display attributes, then adding it again and doing the same things.
This works just fine, but I have a nagging feeling that it's inefficient, particularly for a map service. The consumer of the map service has limited abilities to change rendering.