I have actually done that by accident sometimes. :lol
What about when adding circles and cylinders? My latest model got screwed up when I booleaned cylinders into the model. Also, if you want any kind of smoothness on your circles they make for a lot of little vertices that cries out for attachment...
Edit: After trying the detailing tip three things are becomming clear:
1: It's addicting trying to remove as many vertices as possible while keeping all quads.
2: It's better done continuously from the beginning, not when you have a completed model.
3: rundown REALLY knows his stuff.
Alright, I knew number 3 before hand, but for anyone new to modelling, listen to rundown.