[swatcoder]

> You and everyone else involved will be 100% focused on the task.

That's not the strict positive you seem to suggest. In creative arts, like many of us practice in software engineering, being 100% focused is not the way to get things done. Your conscious, focused attention can only take you so far, and the best work is often influenced by the weird associations and spontaneous insights that come from setting the work down and doing other things.

Now, that's not to say there isn't some extreme on the other end, where you just never actually sit down and write code or whatever because you're always so distracted, but the sweet spot you want to aim for is somewhere in the middle. For many people, pair (mob??) programming is waaaay too far to one side. Although if it works for you as part of a fuller, balanced, practice, you wouldn't be alone in that yourself.