GTD Times: Think once a week

Dear David Allen: You mention you only "think once a week".  Does that mean you have a script rule about planning out your weeks as opposed to day-to-day? Could you explain that a little more?

David: When I say I only think once a week, I'm making an exaggerated point that doing a thorough GTD Weekly Review sufficiently sets up my sense of priorities so that I don't have to do a lot of re-thinking or over-structuring, as I go day to day.  Usually we don't have the time in the busy pace we wo...