We've seen both good and bad public school districts.
Our daughter went to Kindergarten in local district A, had a horrible experience and was extremely bored with what they were "teaching" her. We were discouraged from talking about acceleration options and when the discouragement did not work, we were given the run around all summer until being told "NO" the week before school started.
Side trip to a private school, where one grade skip was done.
Four years later, open enrolled to local district B. Here we found a district that is willing to listen to parents and look into acceleration options. One more grade skip, add in further subject acceleration, and last year they allowed her to take 3 high school classes while still in 8th grade.
What local district B does, in my opinion, is the easiest and cheapest way to deal with HG/PG kids - accelerate them (whole-sale, or subject only, or both). If testing says they are ready for 7th grade, but the calendar says they should be going into 6th - skip them into 7th. If they're ready for Algebra and Biology in 8th grade, send them to the high school (and let them take a world language while they're there). In fact, plan for this and make sure you have high school classes first thing in the morning that advanced middle schoolers might take, and arrange for a bus to go back to the middle school after second or third period. It amazes me how many districts don't do this. If you already have a classroom where Geometry is being taught, and you have a student ready for Geometry, put their behind in a desk in that classroom. If you do enough of this, there won't even be a stigma (or at least much less of one) attached to the kids being accelerated.
In our experience there are both good and bad districts out there. We got lucky that our state allows us to open enroll out of the bad one and into a nearby good one.
--S.F.
