MCU movie legs
As others have posted, legs get worse as series go on (with a minor exception).
OW as percentage of domestic gross...
Iron Man - 31, 41, 42.6
Thor - 36.3, 41.5
Cap - 36.8, 36.6, 45 or so
Avengers - 33.3, 41.7
That's a pretty strong pattern. No sequel on Hulk. GOTG and Ant-Man have a shot to move up on gross, but still follow this patten.
I'm a big fan of these movies and attend OW if not opening night. From deep in the forest, I think these movies are doing well story-wise. WOM seems less of an issue for MCU.