I finally watched Race to nowhere now that its available on Netflix. I had been interested in it since it came out but for some reason it was hard to locate. I’m always interested in criticisms of the American education system which I think puts the wrong emphasis on obedience and busy work. So I was sympathetic to the documentaries main thrust, homework is excessive and of limited educational value. However, the movie was essentially anecdotal. It tells the stories of few families, and blames school work on suicide and mental breakdowns of children. It also seems mostly localized to fairly uniform California communities.
There was one reference to scientific evidence that suggests that after approximately an hour homework efficacy drops. Other than that, there was virtually no scientific or statistical evidence to support their claims. No evidence correlating homework and overscheduling and suicide or mental health issues. No scientific studies comparing different educational approaches and their comparative results.
So yes, anecdotally, it seems like overscheduling children and burdening them with excessive homework is bad, especially for the kids in the movie. And standardized testing and no child left behind seem to have played a role in a shift towards worse educational practices. But if you’re looking for hard facts, or to be convinced, this ain’t gonna do it.