I only worked part-time at college, around 25 hours a week at a local hotel. Every single Friday and Saturday night I spent around 8-9 hours working the front desk and kissing my social life goodbye. The good thing, though, is that after around 7 or 8 things would usually quiet down and I could do my homework or get some studying done in the office. Same thing during a weekday shift - I'd just pick later hours and get a pretty mellow studying environment.
I was also able to juggle my hours around and take the week off when finals came up. If you're having a hard time squeezing things in and can afford to miss a couple of days' worth of work when crunch time rolls around, then giving yourself some hardcore "study time" might be a decent solution. Most bosses with a soul would respect someone who says, "Look, I have a bunch of deadlines and want to keep my grades high." - as long as you give them plenty of notice as to when you'll need the hours cut so they can have someone available to work your shift.