It isn't even necessarily just Chesterton's Fences. The problem can just be picking your battles. Processes that are working well enough for the team don't need to be fixed right away to be better, and that'll dump a bunch of cognitive load onto the team in the short term. If you show up and on day one you want to fix 4 different processes, the team is going to hear that over the next 3 months you want to completely change how they do all their work, while they need to keep the rest of their work going. That is moving a whole lot of proverbial cheese all at once. Of course, teams can stagnate, and some of this can be good, but you need to spread it out, do the politics up front to get people to agree that processes need to get upgraded, and ease them into the changes over time.