Depends where you work. This was one of the more alarming things about getting bought by Yahoo. When Viaweb was in Harvard Square we used to leave the office 2-4 times a day. When we moved to Yahoo, which was in the middle of nowhere, we never left.
2-4 is still probably less than the number of times people visit this site. It's my mistake for not being more clear about this, but I also feel it's less harmful to go out than to visit here. At least going out constitutes a concrete block of time, leaving you with a big block of time to get work done when you get back. On the other hand, many small visits to this site only serve as interruptions to your flow, never allowing you to have a big block of time for work.
A friend once remarked to me that one of his 'cures for procrastination' is to do something only mildly distracting, and mildly amusing, after sitting down to work and both taking on any big problems. He says it takes some time to get settled, but he needs to feel a sort of mental presence of a problem before he can really tackle it.
Perhaps the right type of break is the same way: perhaps it lets you cool it and evaluate your issues before tackling them, instead of following the path of least resistance.
I seem to be highly susceptible to spelling issues and one word omissions while sleep deprived. PG, if you're reading this, consider allowing very small (~one word) edits after posts have persisted.
It's only a hunch, but perhaps after a certain point in time, you could change 'edit' to correct. Upon clicking correct, each word or space (to insert a word or two) becomes hyperlinkable, and if you click on it, you can do inline edits. Validate the changes in javascript, apply when a button is pressed, or focus is lost.
That's probably true. Complete changes in environment seems to clear the distraction build up better than surfing. Plus, surfing easily turns into "just one more page."
Nearly once an hour, I think. I don't keep close track. Plus going out for a run mid-afternoon, weather permitting.
I've found that one of the largest benefits of working at home is that I can get up to pace whenever I feel like it without disturbing any cubemates. I find pacing much better at clearing the head than deliberately going out for a walk, because I do it subconsciously without mentally unloading the problem. I noticed the same effect at work too: when I had a big office to myself, or when my cubemates weren't in to work, I tended to get much more done.
I find I can't concentrate if I've been sitting at the computer for more than 2-3 hours straight. I really do start to feel the lack of exercise.
I usually take a bath instead of going for a walk. Sometimes a couple a day. Then a few minutes after I get in I have some idea, or work out how to solve something, so have to get out again to do it...