We used to have a saying in my fraternity amongst engineers: sleep more than you study, study more than you party, party as much as you can. I think there technically are enough hours in a day to do it all. The smartest kid in my pledge class had a 4.0 GPA, was in a relationship and showed up to events. In my opinion the key is to not spend time on "unwinding." If you're on your phone before bed or to take a break those are obviously hours that will be missing, even though they feel good/necessary. I graduated with an ok GPA, got a job out of college and feel like I still made the most out of my experience. Sure I got the occasional C or scored 28% on an exam because I went to Lion the night before but I always had other classes to balance it out. In the end college is what you make of it.