We all know about the 10,000-hour rule, whereby that amount of practice (or thereabouts) is held to be necessary to fully master a given skill. And not long ago I proposed the 5-hour rule, which is what it takes to pretend to be able to do something on video. Now there is also a 100-hour rule, which is what it takes "to become much more competent than an absolute beginner."
Leo Polovets's angle centers on sales—yes, another VC who thinks he's a public intellectual!—but I think he's onto something with the idea of there being a threshold of competence where egregious mistakes stop being made, and that it generally takes more than two weeks but less than a month to train someone past it.