Just to chime in for those who have Juniors or below-- DS used very little homework time as a freshman and spent most of his study hours doing other things. Sophomore year he took the max number of classes available and homework took a little bit more time. Junior year, the advanced classes filled his schedule and he really started having to use his free period and study hours to the maximum to maintain his grades and stay afloat.
Senior year, there were so many classes he wanted to take (advanced, special interest classes) that he got special permission from the Academics Dean to fill his schedule. No free block at all - Seven advanced courses. I can tell you he is more than using his study hours to keep up with the work and at times has dropped a few of his juggled balls. Meanwhile, his other senior friends took the minimum they needed to and are having fun during ample free time.
So, I think some of it depends on the choices made by the student for which classes they are taking and how many. DS has plenty of classmates that are taking the minimum required and have plenty of free time. He has others that must have the highest grade in the class and they stay up all night, no matter what the course load.
I think freshman year should be what one looks at to really gauge the academic environment/expectation, because after that it really is up to the student and how they craft their schedules.