I am in no way an expert, but the OLSAT seems to be a strange animal. DD learned from experience how to take the test, I guess. IMO, that makes it a less reliable instrument.
I agree that it has a whole host of problems, but ability to learn how to take the test is something that can occur with any ability test. You can raise your IQ scores even with a lot of practice taking IQ tests although you aren't likely raising your intelligence. It isn't recommended that kids take the same tests over and over or too frequently for that very reason. The way your school system is handling it seems rife for a lot of overidentification of giftedness.
There is also a lot of unfortunate test prep going on and I imagine that tests like the OLSAT would be easier to hothouse or prep for than a more controlled test like an IQ test.
