All I know is that if I was a therapist, I'd definitely have to at least take notes after a session. There is no way I would be able to remember and keep all those separate clients and their stories straight. I have a terrible time keeping all of my students straight as it is; I am sure I'd equally suck at keeping all of my clients straight, particularly early on when I have only seen them for awhile. I think some people have a natural ability to remember things like that, and others need notes. Doesn't make either one a better therapist; it just means one has a different kind of memory than the other.