I would say some of both I think. I have 4 children, ranging in giftedness. Oldest is 10 and she is my nerd child, gazillion questions on anything, super excitable, emotional, justice oriented, and was the one skipped at 2.5 yo to the 4-5 year classroom cause she knew everything they were teaching in the other class. Spoke well and often, was able to jump in the middle of lesson/game early on and be right on track with the class no matter what odd thing she was doing on the side.
The twins are 14 months younger, and I was adamate I was going to have them tested for speech delays. They were around 3 when they started speaking well enough to not have to ask them to repeat something (I still think they were speaking some twinish). Took me a while to find out, they were about on track regarding their learning for their age, I was just compairing them to my nerd child. I now think we are dealing with some dyslexia, so I have to stay on top of them and their work (one is worse than the other).
Little man 5yo was just not a talker, and could not make him interested in anything that he doesn't want to do. But he can read and has for about a year now and is doing math on his own, and he is my only coordinated child (even as a toddler, didn't really fall, the only one not to fall down stairs, and good with a ball).
Then there are children who are not exposed and really have just not seen these things before being put in a classroom setting. Maybe the parents wern't exposed, maybe the parents don't know how to teach their children casually about shapes numbers and letters. There are children who don't know what their name looks like on paper or don't know what their last name is, because they've never been shown.
I guess what I'm trying to say is they will all work at their own speed, and that year of kindergarten is really needed for some of these kids, because it might take some of them that long and longer to learn all the stuff they cram into kindy these days. And it took me a while to learn that I can't compare any of my children to each other (including the twins, still struggle with that one) and can't compare them to anyone else. Education is definatly not one size fits all. Once it starts to click for a child no matter the age they will get it.
I'm probably rambling, in the middle of my 3rd day of 12 hour stretches at work lol.
