Personally, I think there is very little a tutor adds to a strong student beyond a couple of sessions. Those can be useful to help the student identify certain types of questions and the best strategy to find the answer.
We used a tutor once a week for an hour, which I would hardly call grinding out. Basically I was paying so my D would actually make brain space for prepping, otherwise there was always a paper, a test, a club meeting that took precedence. My other two were a little more disciplined and the free khan academy practice was great.
As for the notion of prepping, it’s like any other school test. You review the materials before hand. The idea that it’s unfair because some kids are preparing themselves for the test is absurd. Is everyone on equal footing? No. Are kids from the same school generally expected to meet a certain number? Yes.