ACT or SAT scores are extremely important in the recruiting process. Unfortunately the only way coaches can compare kids academically nationwide.
We've done Princeton Review and we've done stand alone, private and small group tutoring. The quality of the instructors vary widely, even within companies. The methodology was similar: get familiar with the test, do practice problems, repeatedly take timed practice sections and tests, review mistakes, etc.
My two guys both did better in the earliest Fall tests of their Senior years. Probably a lot of reasons. One important factor as JCG noted was the ample time to do prep in the Summer.