I am referring to ALL of them from medicine to law to masters programs. Some of my relatives got vastly different percentiles on their SATs and grad school tests. A couple went up ALOT percentile wise (and it was one of the more competitive tests) and the other went down quite a bit in percentiles (also in a competitive field).
I think when my parents took it, maybe it measured intelligence somewhat because although there were some courses, no one worked at it the same way am told. The reality is that kids are going to SAT camp in 8th grade throws everything off. Also I hear rumors about kids in Asian countries (sorry no offense to anyone) where they are drilled until they get to 800. Even the PSAT is not a fair measure because they have courses for that too. Good or bad? No idea but the point is these kids work. I know someone who got over a 2370, he worked alot to get it. His IQ has been measured and it is under 130 (he was not accepted into the GT program that my friend attended).
So my friend from the GT with an IQ at 97% at age 8, will still be just as bright but will not be breaking 2000 without work which he was not willing to do.
Yes people can vary but not 250 points over 8 months unless they work. Plus part of the reason that certain schools want all your tests is that they can make sure you have not taken it a bunch of times in an effort to imporve your score which is exactly what most people do