How Many Scenes?

Q. How many scenes on average make up an act in half-hour comedy?

It depends on the show.

If you're writing a spec episode, get your eyes on a few scripts from the show you're speccing, and count the scenes. That's how many you should have.

If you're doing a spec pilot, get some scripts from a show with a similar format (single camera comedy, sitcom, faux-reality, etc.), and count the scenes.

It's a good idea also to take a look at how many interior scenes there are vs. how many exteriors; how many scenes on standing sets vs. scenes on swing sets or locations; how many scenes have multiple characters vs. how many two-handers. Don't be utterly hogtied by these averages, but use them to check how close you are to what you're seeing on TV.