Malcolm Gladwell popularized the notion of the “10,000 hours rule” in his very readable book Outliers. It goes roughly like this: practice a specific skill deliberately for about 10,000 hours, and you’ll get to world-class level in that thing. The takeaway from that seems to be: pick what you want to do early, and stick with it.
David Epstein respectfully disagrees, and he lays out his arguments and copious supporting data in his book Range: Why Generalists Triumph in a Specialized World. You can find discussions between the two on this topic on YouTube - and in one from February 2020, Gladwell says that Epstein has convinced him.
A great introduction to the big idea is Epstein’s TEDx talk on this topic:
Kind and Wicked Domains
Epstein, borrowing terminology from other authors, makes a distinction between “kind” and “wicked” learning environments.