One of the more charming aspects of the earlier films in the Marvel Cinematic Universe was their overlap. Despite different release dates, "Iron Man 2," "Thor," and "The Incredible Hulk" were all set around the same time, and events happening in one movie influenced the others. After the release of "The Avengers," however, this changed. Now, the films tend to occur chronologically as opposed to simultaneously. Remarking on this different approach, Marvel Studios chief Kevin Feige has stated that there's a good reason this overlap has all but disappeared: Marvel Studios is trying to focus on how individual stories influence the big picture rather than the other way around.
"I think people like to talk about our long term plans, which we certainly have," Feige told CinemaBlend. "But very rarely do those long term plans dictate the specificity of any individual film. It's usually the opposite. It's focusing on a story, and focusing on the individual movie that we're making to do what's best. And then, if something changes that we weren't quite expecting down the line because it was made for a better movie, then we deal with it down the line. I think that's what happened in Phase One. We were telling those stories and having the crossover of Nick Fury talking about the Southwest Region, when the hammer fell..."
Fury's comment on the Southwest Region is one of the more famous examples of overlap in the early films. The S.H.I.E.L.D. director's remarks indicated that the events of "Iron Man 2," where he made the comment, and "Thor," which takes place in the Southwest Region, were occurring more or less simultaneously. There's also a reference to "The Incredible Hulk" at the end of "Iron Man 2" in the form of a screen broadcasting a news report about the Avengers' greenest member tearing apart a college campus.
The films have changed a lot since the debut of "Iron Man" in 2008 and the start of the MCU in its current form. Since then, the cast of characters and number of movies released every year has expanded exponentially, which certainly complicates attempts to create overlap between the different films. While the future of the MCU and the characters in it remain ambiguous, Feige has previously stated that the currently untitled sequel to "Avengers: Infinity War" will mark a "new age" for the universe.