From others experience it's 2 years at good community college and 2.5-3 years at the good state university. I've yet to see state college take all the credits from a transfer.
admittedly i don't have first-hand experience in this, but my understanding from friends & family here in CA is that limiting time at a state university to 2 years (and sometimes less) is entirely possible, with some planning.
the confounding factor for young adults, i suppose, is that it's hard to be certain enough about future interests amid all the possibilities not yet forgone to stay the course without (understandable) alteration (i changed course a few times in college myself).
