Sitcoms.

The conventional sitcom has a 3-act structure.  The first act introduces a problem that the characters must solve.  The second shows the characters trying to fix whatever issue, normally in a humorous fashion.  Finally, the third act resolves the problem and is generally referred to as "the lesson."  By introducing a new problem with each episode, screenwriters attract viewers to see what will happen next.  An example of a sitcom that incorporates the 3-act structure is "The Office".

The most recent episode of "The Office" begins the first act with Jim, Dwight, and Michael losing a sale to Tim Olyphant's character.  In order to fix this problem, the show moves into the second act as the characters set up a sting operation in order to investigate Olyphant's successful sales techniques.  Finally, the show ends and the problem is resolved when Michael Scott abruptly hires the competition: "If you can't beat them, join them."  This episode, like all the other episodes of "The Office" and many other sitcoms, presents a problem, goes through the process of solving that problem, and ends with a resolution.