One of my housemates did this - he'd work 9-5 every day of the week, then have the weekends and evenings mostly off (except during busy times). I think it worked quite well for him, but he stuck to it religiously. Every morning he'd be up early and out the house. It gives you structure, but it doesn't work for everyone. A lot of students work better in the evenings for example. I certainly think some sort of study timetable is a good plan - though lots of people have these and they're gone within weeks of starting back at uni.