The regular school system is cheap because they are standardized, and everyone is treated the same.
From a curriculum standpoint yes, but not from an attention view. Teachers spend most of their time with the trouble students.
The next best thing is to have your child skip grades. That might be good for her studies, but not for her childhood.
I don't think I would want this for her. I would rather her have a steady group of friends her age for now. Plus, she will excel in some areas, but be deficient in others, so if she goes up, she will struggle where she is weaker.
It was later abolished, because of discrimination on students [there was also a last section, where students who are lagging go].
It is funny that being smart is a bad thing. Shouldn't we want the smartest to excel and improve our broken world?