I'm using the Faster University Education mod by Dave Luv at MTS2. There are three options. One semester can be either three, two, or one days long.

I was using the "one day" option for a while, when I wanted to speed all the uni premades through, but the sims have to eat, sleep, breath their course work to get through it (it's entirely possible, though). Two days is nice and comfortable, with extra time for socializing, skilling, etc. I also set all my unis to perma-fall, to help with studying, so that helps.