Huh. I've now run 5 sims through university, and I never had to work on skills outside of class/homework to get an A. The couple of times I've gotten less than an A were when I'd missed large portions of certain classes (usually due to not getting to the door/building on time) or forgot to do the homework once.
I have them get to class on time (or close to it) take notes in class, do the homework, and do any term papers/presentations (which I turn in at about the half-way point in the term for papers, just before the end of term for presentations)
All five University students ended with at worst a high B for the term, and I think a solid A for their time in Uni.
(I also play on long life and have them only take three classes per term, and always start the term mid-week so I have a weekend to work on presentations and papers.)