https://funnyhow.substack.com/p/how-chris-rock-and-jerry-seinfeld

Comedian Matt Ruby relates his personal experience watching Chris Rock workshopping his comedy writing in front of auciences at stress Factory in New Brunswick, New Jersey. Rock would show up unannounced and perform new material in front of small crowds to test it out. He'd read/perform material off of a yellow legal pad.

Peter Sims included some of it in the introduction of his book Little Bets.

This is broadly similar to my own experience seeing Rock at the Laugh Factory trying out material for the Academy Awards as well as Adam Sandler at the Improv on Melrose doing midnight sets reading straight off of a notebook.