However many to complete a reasonable amount of homework/ work so that you're not falling behind. For me personally, I absorb most of the stuff I need in class so I rarely do any homework/ studying at home. It also depends on your commitments outside school.
It really depends on the individual. But if you want a rough figure, I think most people do about 2-3 hours a night.
i would personally say, it depends on what your goals are.also for some people, they want to strive for the best i.e. 99.95. others want to just get their atar enough for their desired course.
as for me, i went home everyday 430 ish and studied till 10 with 30min dinner and maybe a few 10 min brakes. that was because i wanted to get 99+.
so it really depends on your mindset and what your goals are.
As chairs noted, it's about your goals and your own abilities. If you are aiming for 99+, you want to be studying for several hours every single day which would include both studying for exams and doing homework. Some people don't require much study at all to achieve what others would require a lot of study to get because they tend to be good are quickly learning information, retaining it and applying it without much practice. What's most important to consider is your attitude which can greatly impact upon your study habits.