Sounds like it would create MASSIVE incentives to cheat on the IQ test or pay off the graders to give you a good score as well
It would literally set your kids up for life
On the other hand, don't most IQ tests have elaborate anti-cheating mechanisms? E.g., handwriting an ungraded written portion?
It seems perfectly plausible that repeatedly taking IQ tests would likely result in a higher score due to practice and familiarity. Especially if there is a significant financial incentive involved and someone is on the border of qualifying for it.
I'm not concerned with trainability. Lots of minimum bars are trainable, like the bar exam, or the Marine Corps PFT/IST. The fact that they're trainable doesn't mean the measures are invalid w/r/t minimum competence as a lawyer, or minimum fitness as a Marine. Similarly, I don't think trainability on tests of logical reasoning, pattern recognition, reading comprehension, memory, etc. necessarily meaningfully reduces the effectiveness of the tests that measure such things. On the contrary, I think it shows that intelligence increases when exercised.