“Will longer school year help or hurt US students?”
Just a ploy to get more teachers hired, to increase their pay and increase the brainwashing of the children.
More is not better. If you always do what you’ve always done, you will get the same results.
IMO, it’s not the length of time the kids are in school, it’s what is done while they are in school. Simply, get rid of all the extra “crap” that does NOT make them smarter and teach the subjects that do.