I think it depends on the grade/year. In elementary school, I think that's asking quite a lot to give up break time for homework. In middle school, however, it's almost a necessity. I have talked to one of my DD's middle school teachers about this - the problem is, there isn't enough time during the week in class to cover all the material. So, homework and projects over breaks are necessary to supplement the precious-little time they have in class each week.
I'm fine with it as long as the work is worthwhile.
