depends on the person obviously. Some people have bad relationships with their parents or just need a change of scenery. Others are very comfortable with their parents and have no problem being close or even commuting from their parents house.
I'm a little of both. I have a very good relationship with my parents, where I wouldn't mind staying here at all. But at the same time I feel as though if I want to move on with life, it's time for me to leave.