I wrote an answer in this question Why did the story stop after The Dark Knight Rises?
Which got me wondering - why are most superhero movies taken in three parts irrespective of it being DC or Marvel? (I know there are exceptions like Iron Man 4 but hey, if not for the popularity/lucrative returns there would be no part 4, or just two parts cancelling the 3rd if it's not popular/lucrative enough)
Trilogies include --
Spider Man (Actor: Toby Maguire), Batman (Nolan), Wolverine, Iron Man, Wonder Woman, Cyborg(2020 release), Captain America, Thor , Guardians of the Galaxy etc.
So why are super hero movies signed in three-movie deals ?