!! SPOILER ALERT !!
"'You see where you are going - now let's worry about how you get there.' Marvel has been planning their interconnected universe before Iron Man was even released; so they had this massive plan, they saw where going, but they never let that stray their focus. They concentrated... on making good movies, first - and tying them together, second. So, they were always worried about how they would get to the end and what kind of stories they would tell." - ScreenCrush
Marvel shows us that you can be 21 steps away from your endgame - but the more you focus your best efforts on each individual step of the process, the more dynamic the final product becomes.
"Make good movies, first... tie them together, second."
If you made it through the 3 hour Marvel Cinematic Universe finale film, Avengers: Endgame, it's worth 26 minutes to recap [even just a fraction of] the genius references acknowledging the legacy comics, characters, pop culture, and of course, the first 21 films.