I think my T took notes occasionally when she was first starting out being a therapist (I saw her for a total of 18 years and she occasionally took notes in the first 9 but not 20 years later in the last 9). There's probably a bit of what/how they learned to be a therapist and/or experimentation on their part.

My T once got my husband's name wrong and even made a check out to me in my maiden name after I'd been married almost 20 years. At first it's easy to feel disappointed or hurt but when I think about how my mind can "wander" when I'm talking to a person, how I'm thinking of what we're talking about and might throw in a wrong word/name, it doesn't signify? She might have been thinking about how my husband reminded her of this other man (or how I reminded her of another client whose husband had that name) and it turned out to feel slightly endearing to have to think of me "constantly" by my maiden name, the name under which we started our relationship together all those years ago; she wasn't distracted by a name change