In practice, returning to a hard task in this way comes with a ‘restart’ cost: we must spend time and mental effort getting back into our task set, rather than making progress. For this reason, it is important to create time and space for hard tasks.

For example, a hard task such as doing a geometry proof might involve a structured process of retrieving, selecting and checking a set of geometry facts and theorems. The better that the solver knows these facts, and the more effectively they devise an efficient plan to evaluate them, the more readily they will solve the proof. As they do more problems, the facts come to mind more easily, and they follow familiar plans to evaluate each. In general, we can get better at structuring hard problems with experience. This is one reason that practice makes us more efficient and successful at hard tasks, and that experts outperform novices. Finding work habits that encourage this process helps us to stay focused.