.. by the people who started it and popularized it. I have never tried it full time because it's obviously patently moronic to do it that way, and would destroy all enjoyment of the job. I have worked with highly talented developers and can not recall any one of them wanting to pair full time. I have received huge benefits from occasional pair programming with senior developers in my less senior days. However, I need to try full time pair programming as much as I need to try jumping into a fire to verify that it's not a smart idea. If my employer forced me to do that I would quit on the spot.