The few places I've worked in (some small, some largish - 2500+ people) - I've never worked anywhere more than 22 months, so ... there's not always a long time

The few places I've worked in (some small, some largish - 2500+ people) - I've never worked anywhere more than 22 months, so ... there's not always a long time to develop relationships. But... coming in, there are already relationships, sometimes going back years, between people, and it's not easy breaking in to those, or fitting in at all. Without even trying (or specifically because they're not trying), well intentioned managers end up playing 'favorites' with some, which has seemed to exacerbate the issue of 'insiders' vs 'outsiders'.