However, in a previous life as a programmer, I definitely worked this way: I'd get up about once every half hour, go get a cup of tea and do something minor before diving back in. I couldn't possibly sustain focus much longer than a half hour, and if I broke up the focus more frequently, I couldn't finish anything significant. And sandwiched around sets of these (more typically 3 than 4) were meals, stints of answering e-mail or someone's questions and so forth. On days where the interrupts came too fast, I didn't even try to do anything substantive; it was pointless.
The idea that this gets written up, studies, promulgated as A Technique etc. just leaves me all dizzy and disoriented, sort of like Allen's remark about people need to learn how to touch type.