Kevin Feige, the head honcho at Marvel Studios, is a big fan of the trilogy format. Telling serialized cinematic stories in three parts is one of the many ways the Star Wars saga has influenced the MCU. From Iron Man to Captain America to Thor, Feige and co. have generally stuck to the trilogy tradition with their superheroes’ solo adventures. The Avengers series is technically a quadrilogy, but Infinity War and Endgame are essentially two parts of the same story (and were even billed as such early in development), so it has the familiar “beginning, middle, and end” feel of a trilogy.