The homework my son had in 2nd and 3rd grade was ridiculous. Literally 2-3 hours/day. I spoke to multiple parents whose children would cry every night. Once I saw my son "hit the wall," I told him to stop and wrote a note on the homework for his teachers to read.
His 4th grade teacher made it clear that it was important to her for "kids to be kids," (and she wasn't even a parent) and gave minimal homework. Her mantra was, "work hard in school, play hard at home."
Grades 5-8, he had a couple teachers who still gave quite a bit, but most did not.
Once he got to high school, the only homework he's had has been to study.