40 hours per week, 8 hours a day, is the legal limit of hours an adult can work in California without being payed overtime. An employee must be payed 150% their usual salary for every hour they work past 8 hours a day. I spend between 34 and 39 hours per week at school, not counting homework (aprox. 10-15 hours per week). My suggestion is that any work assigned to students requiring them to spend more than 40 hours a week on academics be graded with a bonus of 50% the student’s grade. This would encourage students to do well in order to have a higher bonus, and would discourage teachers from assigning so much work (since we all how much giving out bonus points pains them!)
As for the questions:
I think that homework is effective as long as it will help improve a student’s understanding and execution of course material. As a general rule, I don’t think it’s very useful to be assigned more than one assignment in each category of homework to a class (1 chapter to read, 1 exercise, 1 essay). 5 math exercises is 5 too many if I understand the lesson, and 4 too many if it is the teacher’s goal to find out whether or not I do. As a student, I have a limited amount of time and love to divide up into my work. I find work that leaves the thinking up to the student to be the most engaging and helpful to my understanding: the fewer details on how I should do the assignment, the more I work to make it reflect my understanding of the topic.