 His pursuit of the art offers a master class in mastery. By the time he read that issue of Esquire, he already understood the value of practice. Get this. You'll love this, Lee. To prepare for his first appearance on Johnny Carson's Tonight Show in 1981, Seinfeld rehearsed his six-minute set 100 times. 100 times. That's what Johnny Carson said. The best ad-libs are well rehearsed. You know what you're going to say.