personally i have the same problem, none of my models will be working without splitting it if triangulated
i think that part of the problems comes when you don't realize an original design but you use some kind of reference (star wars, b5....), in this case ppl usually tends to use more polys to render more details that in other situations you don't take care about...mainly because in other situations the reference doesn't have that level fo detail;)
personally i still hate truespace (5.0), point editing is a nightmare and there are a lot of functions missing that would be absolutely necessary, expecially when you join different objects, well even MAX suck in modelling but for MAX there are the famous meshtools, for truespace i was able to find only a single plugin decently working that is able to connect 2 faces with same n° of edges of two different obj's, other points needed would be a more powerful "pointdraw" and a better control of the faces generated (that sometime got screwed)
for all these reasons i'm still as slow as hell when it comes to modelling but i have to say that after a little experience you become able to slightly reduce the number of faces that will require manual triangulization to work in game by modelling in the "right" way (avoiding general errors and faces generated by booleans)
(another tool that would be useful is a triangulate only selected faces:p)