At the last school I taught at 3-3.5 hours a night was considered the "norm".

Personally I think it's just a tad bit excessive.....

Homework should only be given when it's a meaningful extension to a lesson and not just take up your time plodding through worksheets for the sake of homework.

You do need some "down time" each day when you're away from school and the textbooks in order to recoup your mind.