The 10,000-hour rule of thumb
Listen, do you want to know a secret? Do you promise not to tell? Closer, let me whisper in your ear . . . —“Do You Want to Know a Secret,” from Please Please Me, 1963 By the time the Beatles brought the “British Invasion” to America, in February 1964, and my family watched them on the Ed Sullivan Show, John Lennon and Paul McCartney had been playing together for seven years. By a fluke, in 1960, “when they were …