In most of my other roles, I think I've often become a valuable contributor being able to "pull their own weight" within 1 to 3 months. On a number of occasions I think joining with a "fresh mind" who will say "you guys are doing what?! lol that's crazy, $this is so much better!" has been a real advantage, sometimes even in the first week. I'm not trying to paint myself as some sort of rock-star developer or anything, but in small teams people can get kind of stuck in a sort of an acceptance of the suckage they have, even when it's not needed. One example of this is adding a real database migration instead copying SQL queries from the company chat. Simple stuff really, but does make a meaningful difference.
I do think longer tenures are an advantage because people will have to live with their choices. I have a former co-worker who brags about what he did when he worked for us as being brilliant to this day, but we literally threw it all away because none of it actually worked well; it was complete garbage. But he never stayed long enough to have to deal with any of that.