Take Interview with the Vampire for example. Tom Cruise Brad Pitt. Movie was a monster hit demanding sequels and the two never appeared as vampires again. You would think studios would have been chomping on the big late 90s early 200s for a reteam but never happened. They were also rumored for Go Like Hell which eventually became Ford v. Ferrari with Matt Damon/Christian Slater.
Robert De Niro and Scorsese by 1995 had done 8 movies together and had a long standing working relationship. Yet they didn't work together till 2019 a 24 year gap.
I'm sure there's other examples but why does it take forever for these actor/actor actor/director combos to get off the ground. The press releases always say "scheduling conflicts" but I'm like how busy can they be being on big boats with models? Basically momentum is lost by the time lapse. A movie like the irishman should have happened in the 90s with the three main principals at their peak not decades later when they're in their late 70s.