I have a class in which there are several methods that can act as an “entry point” to its private innards (or the “fruit” thereof).
Said functions might be called multiple times throughout a single “pipeline” as triggered by such an entry point, but only the first call should act as the actual entry point in that it performs a certain initialization action.
Similar use cases show up in situations that aren’t necessarily object oriented, of course (off the top of my head: wrappers of recursive functions which initialize something before the recursion itself begins).