But why care more about the scores when kids are getting scores that are good enough to get into most colleges?
IIRC, when we studied these prep-tests in psychometrics in college, we learned they make very little difference overall. I don't recall exactly, but research then showed the prep classes only improved scores by an average of 1 or 2 points. A well designed test should accurately measure your intelligence and academic knowledge without you having to "study" for it. You either know the material well enough to be randomly tested on it or you don't. Teachers would do a review, etc. In grad school, they recommended re-reading your last textbook for any subject you felt was your weakest, but that was about it.