I think if a child is really super gifted, it doesn’t matter if he or she skips a few years or not. That child will study on his own (because of his massive curiosity) and will move at much a faster pace with his own study (not just 1-2 grades faster, but 5-10 grades faster). If your child doesn’t show that sort of interest, it’s best to just leave him or her grow with his/her peers.