I understand what you're saying about work projects but I'm not so sure that I agree. There is a big difference between a general work project and one where a client is spilling their guts to you about very serious situations. I would think Human Nature would just make the therapist think of us a lot more then someone would think about a general work project.

For instance if one of your colleagues confided in you something really big and personal, you'd be much more apt to think of them between the times you work on the project with them then if you just talked about random everyday stuff and the project of course.