That's considerably more than what I'm doing, but I guess we have different aims. Just don't push yourself too hard
I generally do about an hour before school, then about 2-3 hours after school Tuesday and Wednesday. Monday and Thursday I have work after school, so I probably do about 30mins at work if its not too busy, and maybe 1 hour afterwards. Fridays I only do the morning session, while on weekends I go for 3-4 hours a day.
Of coarse sometimes extra if I have SAC study, assignments (prac reports etc.) and sometimes less if I'm in a cbf mood. In fact my regime varies a bit.
I find I don't procrastinate much, unless its a piece of writing for English. Today for example, I've been sitting at my desk for 3 hours, all I've got to show for it is one and a half paragraphs...