How Much Homework is Too Much?

Over the past years I have been noticing a trend in elementary aged students, especially the younger grades. This trend deals with the amount of homework that they are being assigned. I have been surprisingly taken back by how much homework is assigned to these students on a nightly basis. After working at an afterschool daycare, this problem started to become aware to me during homework time after school. I watched as young third grade students did tons of practice math problems that were all exactly alike and then answered several reading questions after being assigned to read as well. In my opinion this homework trend is a little excessive. Children are in school eight hours and now days extra activities such as recess, PE, and music are being taken back to the minimum time, therefore these children are learning for the majority of these eight hours. I do think that children need to practice learning outside of school and that this type of "on their own" work helps the children to build responsibility for their own work, however there is not a need for excess work in multiple subjects. Students need to take this time outside of school to have their own playtime, family time, and time to do other extracurricular activities and hobbies. Homework should never have to take them all night especially and ages and grade level should be taken into consideration.
Now I am not saying this about all teachers, which leads me to another point. I feel that there is a huge inconsistency amongst different teachers with the amount of homework. Some teachers load their students down with books and work at night while others barely assign any at all. Does assigning more homework make them a better teacher? Does it mean that their kids are smarter or learning more? These are questions that I have been curious about for a long time and as an upcoming teacher would like to learn more about from previous teachers.