Other than introducing and using the Time Stone (which obviously was critical to IW/EG), I can't remember a lot of connections. I did a quick search, and it looks like the other main tie-in is for something called The Living Tribunal, but I don't recall that in any of the movies.

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Finished watching with the exception of Ed Norton Hulk, Ant Man and Wasp and Spiderman far from home


Infinity War and Endgame were a lot more enjoyable (I already liked them) knowing all the back stories.

Most of them were good highly rewatchable movies.

Thor Dark World, Captain Marvel and Antman are the only ones I probably would never watch again.