Hi Natalie ...
I hear what you are saying ... and acknowledge that the amount homework a student regularly brings home can vary greatly from school to school or even teacher to teacher. I know some schools and Boards are even going so far as to implement a "zero homework" policy. Personally, as both a parent of two myself, I think that is going too far the other way. That being said, I'd like to offer a few general thoughts and questions for consideration on this topic ...
"10 minutes a night per year" is a general guideline. In my 14 years as an elementary school teacher, this guideline has worked quite well with the understanding that this time may include activities like studying for tests, reviewing lessons, reading, unfinished assignments from the day's classes, etc. It is not meant to represent the amount of assigned homework given by the school. In cases where the amount of assigned homework seems heavy, a conversation with the teacher(s) may be a good idea. What are some of the reasons for the homework? Is a student experiencing difficulty learning? Is behaviour or lack of attention a factor? How much time in class was given for the assignment? How long ago was the due date given out?
How is his/her schedule? These days many kids and families are so heavily scheduled with sports, clubs, play dates, and outings that much of the "free time" that existed in decades past no longer exists. Is there time built into every evening to complete school-related work or activities?
Use your judgment. As a parent, you might consider "cutting your child off" ... that is to tell your child he/she has done enough for one night. In those cases, a note to the teacher explaining would likely be well received. Again, if this becomes a regular occurrence, a discussion with the school might be advised.
Don't believe everything you hear. It is amazing how stories can change when you sit down and call the teacher or stop in for a quick visit after class one day. You may find that important details were left out by your son or daughter like the fact the assignment was given a month ago and he/she left it to the last minute, or time is being wasted during class ... or additional time to work on assignments or help was offered but not take advantage of. While this is not always the case, many parents are surprised.
The bottom line is that you know your child best, so if something doesn't feel right, then I'd invite you to ask some questions and start a conversation ... :)