Is Curb entirely ad libbed?
It seems to me the show is almost entirely ad-libbed. Well, turns out it is, kind of. He says the writers (and Larry) develop an outline for a scene-- ("I have to ask you out to dinner but this is the problem...") and then they ad lib the scene. Then they ad lib it again. And then again. And then they take the best parts of the ad libbing and actually start doing the scene the way they want it.
So by the final take, Danson says he's "back to being an actor." Meaning, he's back to working off a script, albeit a script they formed on the spot in previous takes. He says it's some of the most fun he's ever had... just don't tell Larry.