Broadly speaking, there are two distinct types of television dramas: procedurals and serials. The former, often set in a courtroom or police station, specialise in predictable structures with self-contained storylines that typically revolve around a different case or crime.
Networks and advertisers love them, because (particularly in the age before streaming and digital recording) they were primed for viewer retention. If you miss one episode of NCIS, it doesn't really matter. Conversely, serials allow space for narratives to build and characters to develop over multiple episodes or even seasons.
