DS had 5s on APs in subjects in which he had a B (or B-) in the class at a rigorous BS. I think (but cannot know for sure) that this may have reinforced that there was no grade inflation, and maybe the opposite, at his school. He did fine in the application process with a GPA that was far from exceptional and I suspect that his AP scores may have helped. We’ll never know for sure on that.
The benefit was that he could skip college courses he’d already taken at BS (no credit, but placement), and that was attractive given everything available at college. AP scores can also allow a student to meet a FL requirement or distribution requirement without taking class. I think it’s worthwhile. Why spend your money and time twice on the same thing?