Within a 90-minute focus cycle, it is not expected to maintain focus for the entire duration, as the beginning and end may involve fluctuations.

“I suggest that people do no more than three and ideally it would be two or just one of these 90-minute cycles. Why did I say ideally? Well, they are very taxing. You are in a very narrow tunnel of focus. So for me, I can do one mid morning. I can probably do another one in the afternoon. This is not the kind of work that's like checking email or text messaging or social media. This is very focused hard work, working on hard problems of various kinds, and this will be different for everybody. So I recommend that they be spaced by at least two to four hours and most people probably won't be able to handle more than two per day.”