What's really funny .. is that 15% time commitment, is often "what you're supposed to do". Go to class, do the assignments, study a bit for the exams, and it's really easy to get B's or better. Don't go to class, don't do the work, and C's or worse are pretty much guaranteed.
I got a cousin just staring University .. he asked for advice .. all I said was "start with going to class. Once you are in a routine of going to every class, then I'll give you the next piece."
I never understood not going to class and "dicking around." Schools cost a lot of money. I didn't want to miss anything, and I sure as heck didn't want to get C's or worse. Sometimes, people can be idiots. Laziness can make a failure out of anyone.