There would be very few scores from before 9th grade out there, since you have to ask to keep those.
I have seen a few colleges say they like (but not a requirement) scores to be from 11th or 12th grade. I believe they want scores that reflect what a student currently knows/recalls. I have heard very advanced kids say they forget a few things on SAT Math II if they take it years after they are frequently performing such calculations. Of course, a quick review of pre-calc/trig facts would solve this. It may be more relevant to something like the World History test. If you took that in 7th grade and never touched that subject again, how much would you remember 5-6 years later?
I think it is okay if a bunch of kids are getting a "top score". The Subject Tests are meant to show a level of understanding/competency in a subject. Sometimes you can place out of courses with a certain Subject Test score (most common in foreign languages). Also, a high score in something like English Lit can indicate that an international applicant has a good command of the language.
