The Russo brothers have been extremely secretive about the Avengers: Endgame. Even in the trailer and the one teaser that followed, we were barely given a hint of what is going to go down in the film. 

BGR

But, according to a report by Collider, the Russo brothers have revealed that the movie is going to be 3 hours long. 

Game Spot

And if you believe in the words of Anthony Russo, the movie is so good that during its screening, the audience didn’t even take any bathroom breaks. 

We have screened the movie four times for audiences now. For the first three screenings, not a single person got up to go to the bathroom.
Vulture

Russo also spoke about the 3-hour runtime, which is the longest of any movie in the MCU till date and said

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. 

He further added:

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.
IMDB

Avengers: Endgame releases on the 26th of April. So be sure to book your tickets way in advance.