It isn’t experience that sets top performers apart but the amount of deliberate practice they put in. Although Ericsson would become associated with the Malcolm Gladwell–popularized 10,000-hour rule—the notion that anyone can become an expert at anything by practicing for 10,000 hours—his actual findings represent something quite different. Expertise is not about a certain number of hours practiced. Rather, it’s about the type of work that fills those hours. Practice doesn’t make perfect. Perfect practice makes perfect.