Now if you were to run Avengers: Infinity War and Avengers: Endgame back-to-back in a seamless, almost six-hour mega epic, that’s a situation that most definitely would call for a break in the middle.
In fact, you could probably run that event for the first week, and people would volunteer in a heartbeat to witness it.
Again, unless the inclusion of an intermission is organically written into Avengers: Endgame’s story, I don’t believe throwing one in for the sake of having one isn’t going to do the audience any favors.
But Endgame as a solo film is an occasion that just doesn’t require a short five-minute suspension of plot and action in order for the audience to either take a break or decompress from what they’ve seen.