It’s tough for many people to block off four contiguous hours for focused work, and even harder for many to avoid spending much of that time checking email or social media. But these things are doable, fairly mechanically: schedule the time; turn off the WiFi; block the web sites; etc. The trouble is that this isn’t enough. It’s relatively easy to zone out—not in a creative day-dreaming fashion, but in a scattered, dull fashion.
It’s very difficult to actually maintain your sharp, vivid attention on a problem for hours at a time. But that’s what’s necessary. Getting to the desk and clearing obvious nuisances out of the way is only table stakes. One hour of high intensity will often produce much more than five hours of dull focus, even if the latter includes no gratuitous distraction.
Process over product, and one solution is to focus on measuring inputs instead. Measuring the time spent on a problem is a good start (see e.g. notes on Pomodoro technique); measuring the time spent authentically, without distraction, is better; but really what matters is closer to “time multiplied by intensity”, as Cal Newport observes in Deep Work.
Getting this intensity depends on more than just the right behavior during the actual moments of work: