Most people stop at "acceptable" skill levels

Most people stop at acceptable skill levels. They reach a certain level in performance and then they stop challenging themselves. It is common that, in most fields, the degree of expertise is measured in years of performance in that field. When going to see a doctor, for example, most people would like to avoid seeing the “young” doctor because of the lack of experience. However, it is the older doctors who have stopped learning. They no longer deliberate practice. They have reached their quota of learning and they no longer challenge themselves the same way that fellowship or medical school would have forced them to practice. It is more likely that the person practicing for 20 years is worse off than the one who has been doing it for 5 years because the automated abilities of their mental representation degrade with the lack of intentional practice and going outside their comfort zone of their current skill level.