We can get greater quantities of every other resource we need, except time. [Peter] Drucker reports that executives spend their time much differently than they think they do and much differently than they would like to. His solution is to begin by measuring how you spend your time, and compare it with an ideal allocation. Than begin to systematically get rid of the unimportant in favor of the important. His suggestions include stopping some things, delegation, creating policy decisions to replace ad hoc decisions, staying out of things that others should do, and so forth…One of the best points is to give yourself large blocks of uninterrupted time to do more significant tasks…

Drucker argues that we should focus on what will make a difference rather than unimportant questions. Otherwise, we will fill our time with motion rather than proceeding towards results.

From A review of The Effective Executive: The Definitive Guide to Getting the Right Things Done by Drucker.