Mine is very rarely late, but it wouldn't bother me because she goes over a lot, plus I don't pay for therapy.

However, a long time ago (I think I was 19), I saw a therapist who was constantly late, 20+ minutes and I would have to wait in the hallway of the building. She would also do things like cancel sessions to volunteer in the library at her kids' school. Now I think about it, it was super unprofessional and I think that it can send a message that you don't matter. I have such strong abandonment fears that the problem with me was the constant fear she just wouldn't show up.