There is actually some good research behind the number, which is just given as a rule of thumb. The other rule of thumb figure is 10 years, which is much easier

There is actually some good research behind the number, which is just given as a rule of thumb. The other rule of thumb figure is 10 years, which is much easier to conceptualize. 1000 of productive hours per year. Basically it encompasses a jumble of things that includes passion, patience, practice, and persistence. The 4 Ps is a coincidence. Of course it's not a magical threshold, but when you can do something (in a focused and conscious manner) for 10 years, it's not hard to imagine that you have reached mastery. The crime of fluffy writing (dunno about Gladwell's new book; didn't read it) is taking rule of thumb numbers and citing them as precision numbers as a way to seem exacting and scientific.