They need to leave after the second PIP, having passed 2 PIPs the manager bears a lot of scrutiny "are you sure they won't regress again? It has been a year and you can't make a decision"

That said I've seen in sales a person only deliver above average when on PIP, passed the PIP and immediately mentally check out then PIP again and deliver. It was pretty maddening for his boss, the person was obviously skilled/capable but just needed PIP to be motivated to actually work