I am seeing the opposite in my area (Sydney, Australia). Our son is early entry and non in his class have been held back. Some are 12-14 months older but is hard to notice a difference between him and his classmates. I do like hearing about the redshirting on athletic grounds because I am yet to hear a highly successful athlete put his or her success down to the age they started school. As far as I am aware it usually more like natural ability, time and effort that leads to athletic success, not age compared to kindergarten classmates.