I think that repetition can be damaging when used as a blunt tool without much thought on the part of the teacher. Take the worksheet problems DD8 had been doing frequently until this week. Last week's she had to do 20-35 problems of the type 64*3 per night.
What would happen if your daughter just did a smattering of the problems to show she knew how to do them, and you explained this in an email? In a system where there is no ability grouping and no acceleration in grades 1-5, so that placement depends entirely on age, it may be rational to blow off pointless work.
I have not had the guts to do this with my children, and I suspect that my wife would be eloquent in her opposition.
