Yeah, that's true...but it doesn't explain why programmers are almost never late for lunch. That's also been true, in my experience. And moreover, it's nearly universally true that the folks who complain the loudest about interruptions are the same ones who are johnny-on-the-spot for coffee-break, games, etc.

In fact, a more cynical person might say that it's all about avoiding unwanted work. Ahem.

Whether or not you believe me, the important point is that yes, it's a decision of culture: at some point, you establish a culture for your team. If that culture includes a maximum latency for code-reviews, then the people who don't like to do non-coding work for days at a time can go code in a cave somewhere else. People who can't be "interrupted" with reasonable non-coding communication activities tend not to be very good collaborators anyway, and probably aren't a good fit for a growing team.