Getting work done going to the gym or even chatting to your course mates is not only beneficial to your classes but also to your social life as a commuting student your social life will be negativity impacted no matter what you do and you need that net work of friends ant uni more than ever. You will also hear about events going on that you may want to go to or later on even go house hunting with people from your course if you choose to move out next year.
It will also help you feel more part of it so to speak and make uni seem less like collage or sixth form.
Staying at school for a while could help a commuting student get things out of the way when he/she goes home. For example, I commute to UC Riverside everyday. When I don't have classes I do homework for three hours and hit the gym for one. Therefore, when I get home, I could do chores and/or rest without worrying about four hours of important things for myself.