I agree with you STEM, my '21 WANTED even DEMANDED to take the SAT in August and didn’t want to have to study during the school year. Different strokes for different folks. Well, now we’ll have to do both (summer and spring). 
My oldest, now a soph in college, wanted to take a 1-month intensive Calc AB course immediately following the end of the school year in early June several years ago. I don’t know why. I had nothing to do with it. I swear.