I don't typically study on Sundays, although there are exceptions.
I commute ~35 minutes one way to school, so I get there 7-7:30 AM and always stay until 4-5:30 due to classes. I usually spend the first hour drinking coffee, checking e-mail, or just doing something that I want to do to get my day started. Due to the huge metro area commuting is very difficult, so it's much easier to get there that early than an hour or two later.
Other than that, I do all of my reading, homework, and the majority of working problems during that time period. I don't have Friday classes and I also go to campus most Saturdays, although that's typically 10-3 or 4 rather than all day.
It works for my classes, because it's very difficult to determine the line where you can just cross it and still be successful rather than do far too much work and know that you'll be successful. I typically develop a very deep understanding of the subjects and have been getting excellent grades. One time it really paid off was when only 2% of a class received an A. Other times it has certainly been overkill.
Other than that, I'm most certainly (over)compensating for the fact that I know I could/should have done it my first time in college and didn't. It's personal, but it feels good to both work hard at it and be successful.
I know many people talk about maintaining a balance, but I'm 29 and married. It costs me a lot of money to return to school. I work very hard only at school during the semesters, work a job during the summer, and enjoy time with my wife and friends in between. If I could go back to my original trip to college, I'd have worked at it like I am doing now. Personally I consider it a much better idea to do the hard work and sacrifice for a few years while you're a poor college student, be better prepared when you graduate, and then have fun when you're working and can afford to. But it does take a lot of motivation, which can be difficult for those that haven't been in the working and/or family world before.