One of mine is at a small independent day school in MA (focused not at all on sports, but very much on academics) and don’t think they have any re-classes in their grade. I haven’t met one, at least, and I have met pretty much all the families. (Some may have been redshirted for K, I wouldn’t know that offhand). I do know a 10th grade transfer a few years ago that did re-class.
I think different schools have very different philosophies and sports plays into this a lot!