I'm a giant procrastinator, so it varies night by night. Sunday, I'll probably put in 2-3 hours doing hw due Monday morning. I have nothing due on Tues, so unless I have a test that morning, I just chill. Tuesday night (ie, right after I finish writing this), I'll probably do 3-4 hours of work. Usually I get started earlier, but I fell asleep this afternoon at 3, woke up at 8, and then had a two hour long dorm league football practice. I went out at 10:30 to grab dinner, and now I'll finally get around to doing homework. I've got a physics lab due on Thurs, so I'll be doing a couple of hours of work tomorrow. Thursday is the big night of work as I'll probably do 6 hrs+ of math homework, compressing a whole week's worth of work into one long night. Average it out, and I probably spend 2-3 hours a night. Of course, there's always things that pop up, for example I spent 4-5 hours on Sunday writing a paper in addition to my regular Monday homework.
Aerospace Engineering major, sophomore year, btw.