There's an interesting retrospective piece about Rodney Dangerfield, in this past Sunday's New York Times Magazine.
Writer AlexThe one-liners were impeccable, unimprovable. Dangerfield spent years on
them; he once told an interviewer that it took him three months to work
up six minutes of material for a talk-show appearance."
https://www.nytimes.com/2018/01/26/magazine/letter-of-recommendation-rodney-dangerfield.html