I've never seen a therapist for just one session but I did see one for 5 before deciding it wasn't going to work. We just didn't click and I realised that I needed a different type of therapy than what she was offering (but I didn't realise this until we had about 4 sessions). The other thing that I didn't like was the room. It just didn't feel comfortable for some reason. My current T has a really nice room - very cosy but still "professional", it even smells nice .