I think you are over-simplifying the situation. Malcom Gladwell's book Outliers popularized the notion that a person needs on average 10,000 hours of practice to truly master a given task. A lot of people took this to mean, "if you put in 10,000 hours of practice, you will become a master." This is not true. The 10,000 hours of practice is necessary, but not sufficient. The practice has to be _intentional_, guided, goal-oriented practice. Not just playing the same song or making the same shot over and over.
That was exactly my point. It is harmful to believe that mindless practicing, or pottery, will make you a master just because you put in the time or prescribed number of pots. How am I oversimplifying?