In _The Age of Agile_, Stephen Denning explores companies that have embraced an Agile Culture. One of these is a software company, called Menlo 
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He describes four different characteristics of their Agile culture, one of which is their deep commitment to pair programming, a practice that is a key component of Extreme Programing (XP):
>A third striking feature at Menlo is the use of pairing: All work is done in pairs. To traditional managers, having two people working on the same computer and doing the work of one is unproductive and inefficient, almost by definition. Managers think pairing must be cutting productivity in half. Sheridan says it’s the opposite. Menlo does all its work in pairs precisely because it’s so productive. > > Performance measures show that it is up to ten times more productive than working as individuals. > > Earlier in his career, Sheridan would have bosses who, when they saw two people working together, would assume that at least one of them wasn’t working at that moment, and probably both of them. They would inject themselves into the conversation and make those people “go back to work.” Menlo is the opposite of that. “It’s only if we see someone alone,” says Sheridan, “that we are likely to ask: ‘Why aren’t you working?’” > > Denning, Stephen. _The Age of Agile: How Smart Companies Are Transforming the Way Work Gets Done_ (pp. 63-64). AMACOM. Kindle Edition.
Perhaps one of the primary reasons that the practice of pair programming is so effective is that it allows developers to enter into a Collective Flow state.