Pair programming is one of the smartest inventions in this field, but I wouldn't dream of advocating it for this reason.

The best model would be four hours of pair programming and another four of paying those programmers to take a long lunch, a nap and a walk. Those 4 keyboard-hours would probably be as productive as 16 keyboard-hours of the same programmers working independently for a full day, if not more. And unlike full time pair programming it would be sustainable.

I don't disagree, but like all business initiatives it's really hard to convince my boss's boss, that I should be able to sign off and work half the amount of hours for the same paycheck.

So we have to "play" the game of looking busy and appearing productive for appearances.

Maybe the best for you. I enjoy a couple/few hours of teaming up or conversation, and then a heavy rest of the day solid coding/planning/research with a lunch break and a few short water cooler meetings.

3 or 4 is just fine. I worked at a place that only did pair programing, but quite often we would break up to write docs fill out jira issues and do all the other stuff that's needed. Recently we did 3 way programming once a week for 1 to 3 hours and it still had a lot of the benefits. Not sure being absolutist is a good approach to anything in our field.