My girlfriend was using her calendar as a todo list for quite some time. Like many of us though, interruptions and various curveballs meant that she had to regularly spend time moving uncompleted items forward. After seeing how much time she was burning just shuffling things around, I started pitching GTD.

One of the qualities of a good organizational system is that it shouldn’t demand a lot of additional work just to keep it maintained. I keep time-flexible tasks out of my calendar not because it is The Word Of David, but because he has good reasons for his advice and those reasons apply to the sort of work I do.

In addition to interruptions throwing me off, scheduling my work would be problematic because I don’t necessarily know how long each task will take. I’m a programmer and my profession still isn’t very good at time estimation. To make matters worse, some tasks are inherently unquantifyable.

To understand this, consider losing your car keys. How long will it take to find them? What percentage of the search have you completed? There is no meaningful answer. You look for your keys until you find them. Until then, all you know is that you aren’t done.

While scheduling all my todos is a non-starter for me, I do find the daily todo list to be useful. Some days I select a few items from my Next Action lists that I’m going to try to crank through over the next few hours. It is helpful to have a concrete goal to shoot for. If I’m not able to get through the whole list, that’s no big deal.