Optimal Pair Swapping: 90 minutes

Promiscuous Pairing and Beginner’s Mind: Embrace Inexperience "It often takes days for a given pair to be comfortable enough with each other to be able to achieve Pair Flow at all. This means that pairings tend to be long. The longer the mean time between pair swaps, the less effectively pair net distributes information through the team."

"While two people are paired, they share knowledge. When the pair splits for a pair swap, the knowledge then spreads to all four participants. In this way, knowledge will slowly but automatically spread around the group."

And the surprising result:
"This makes it easy to see the shape of the curve near the 90-minute optimal point. However, we did note that longer pair times had slightly higher mean velocities."

So you think you're doing extreme XP and someone always has to crank it up one more level. 90 minutes seems pretty close to me to be the minimum period of time to actually get a chunk of work done - considering that getting work done by yourself usually requires an hour.

I was actually looking for evidence that pair programming's flow state is better/worse than normal. Specifically,

• How much more or less is "pair flow" susceptible to interruptions,
• Whether pairs are able to resume, after interruption, more quickly into a shared flow state,
• Whether it's faster or slower to get into a "pair flow" state, and
• The effects experience has on the above.