The chess example is Polgár, I assume?

I'm actually a bit skeptical of the idea of early specialization. I think it makes sense is "kind learning environments" like chess and sports. But generally speaking, most people who go on to do exceptional work tend to have a fairly long sampling period where they try different things: because you can go further if the thing you do fits you perfectly and excites you profoundly. I remember seeing, for example, a study on professional soccer players, and they did actually play less structured soccer than their peers early on - instead trying many sports and playing a lot of unstructured soccer - only accumulating more soccer training hours in later teenage years.