"I've Pair Programmed for 27,000 Hours. Ask Me Anything"

Pair programming works pretty well...just not full-time. I think the optimal situation would be half-days or maybe less depending on the pairs and the situation. Also, some more mundane tasks (bug-fixing) aren't going to be handled as productively when pair-programming.

The ideal situation seems to be at the beginning of a big story. Then there seems to be a natural time into a story(stories) where it makes sense to split up and work alone.

In your experience, besides efficiency, speed, stability, scalability, robustness and the like, what is the effect on true innovation or doing something groundbreaking?