I'll add another: you tend to miss out on some of the inner workings of the system when you have someone there to answer questions instead of diving in and figu

I'll add another: you tend to miss out on some of the inner workings of the system when you have someone there to answer questions instead of diving in and figuring it out yourself. Yes, in an ideal world you have both, but doing lots of pair programming makes it too easy to take the shortcut and just ask how to do something, instead of learning the fine details of the system such that you don't have to ask those questions anymore in the future.