Not everything needs to be a franchise and maybe some movies don’t need sequels. Some movies might be okay with a sequel but multiple sequels might be pushing it. Some movies might be good as stand alone movies.
Maybe I don’t have franchise fatigue. Maybe studios just want to make a lot of franchises. There seem to be plans to make a whole series of Ghostbusters movies (with both sequels and spin-offs) before the new movie comes out. There are plans for a Universal Monsters series.
Is Marvel’s cinematic universe partially to blame for this? Maybe. I think they were the first studio to use the phrase Cinematic Universe. Now other studios like to use the phrase too.