To answer your question a model does not need to be a single unified piece of geometry like a single perfectly joined polygon.
Here is a model that I made that is basically polygon boxes and other primitive objects all stuck into each other. This is common for these type of models (see Kurt B's assault mech tut).
https://srv01.simply3dworld.com/showt...threadid=25308
That being said the topology should be clean (no floating verts, non-manifold geometry, co-planar faces, faces with zero surface area, etc. These are the things that cause Maya's tools to malfunction and others done the pipeline to want to put a hit contract out on you!
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675
Last edited by ctbram; 10-12-2009 at 12:32 AM.