Sure Tallica play the standard tunes but they play 2:30 hours shows. Sometimes even longer than that. they also play around with the playlist from gig to gig. So it shouldn't be that difficult after all, who really cares about the backdrops in 2022.
Maiden try to change setlist in 2010 and it didnt work well. And it is huge difference between 4-man and 6-man band for that kind of experiments.
Metallica also rehearsing songs before the show so they can easier rotate setlist. I dont think that Maiden spending too much time together before shows.
I already posted few days ago that for example half of the band came in Belgrade day before, and half of the band came only 3 hrs before the show.
Also in Split 2008, the show was late because Bruce went to Rome on the day of the show and he had some problems with airplane so he was late for the show. So I dont think that they are worry too much about setlist during tour, they are busy with golf, flying, pubs and sightseeing