I play weekly with a group of friends that’s been playing together weekly since 2007 (we’ve known each other much longer), changing games as we get “done” with each one. Last Epoch would be next in line for us if only we could all 5 play at once; as it is, it’s our fallback game for when one of us can’t make it, which is not very often.
I know 4 is the tradition, but is not universal. PoE, for example, allows 6.