You Call the Handyman (South Park) - spot on commentary as usual (Public Board)
B plot
I noticed that's one of the hallmarks of good writing versus bad writing. Good writing will always have a solid B plot.
One example is the current season of Rick and Morty. There was zero B plot in the first 3 episodes. If you look at the "classic" episodes from earlier seasons, most of them had a solid B plot.