Hours and hours of practice are necessary for great performance, but not sufficient. How experts in any domain pay attention while practicing makes a crucial difference. For instance, in his much-cited study of violinists — the one that showed the top tier had practiced more than 10,000 hours — Ericsson found the experts did so with full concentration on improving a particular aspect of their performance that a master teacher identified.
Ideally that feedback comes from someone with an expert eye and so every world-class sports champion has a coach. If you practice without such feedback, you don’t get to the top ranks.
The feedback matters and the concentration does, too — not just the hours.