The MCU has always been modest with the length of its films. The visionaries behind the films have always valued streamlined storytelling over bloatedness, with most of the films clocking in a little over the 2-hour mark and Avengers: Infinity War being the longest one at 2 hours and 29 minutes. With Avengers: Endgame, however, that might be topped. Word on the street is that the 3-hour long rough cut tested well in early screenings, according to the Russos themselves.
I think the studio is down with what the best story is. Right now, we think the movie is playing well and we’ve had great responses from our test audiences and we’re feeling very good about where it is. We’re still doing work to it. We’re not done with it. Again, this is a culmination film of 22 movies, it’s a lot of storytelling to work into it. Emotion is an intrinsic part of that to us. When you have to tell a really complicated story and you want strong emotional moments with the characters, it just requires a certain amount of real estate. This one, in particular, feels like three hours worth of real estate.
While still far from what industry people call a picture-lock, Disney’s support for the telling the best story possible and the test audiences responding positively to a longer film, it’s looking more and more hopeful that the generous 3-hour runtime may be given to fans. This is the final film of a decade-long story, after all, so it’s apt.