Seinfeld (1989)

The Chinese Restaurant (season 2, 1991) Jerry, George and Elaine wait for a table, in real time, for the whole episode, and then leave. That is the entire plot, and it is the point: with no scene changes to cut away to, every small humiliation of waiting has to play out at full length, and the audience waits with them. NBC executives who read the script reportedly thought pages were missing. Kramer is absent because in those early seasons he was never seen outside the apartment building, so the trio carries it alone. Start here if you want to see how little a sitcom needs.