In Getting Things Done, after the first step of simply writing down each task you want to accomplish (can be of any level of difficult and time), and then you do a seperate processing step after that.

That is when you decide how long each task takes, and if it takes less than 5 minutes you do it now. When you get into the GTD system of life organization, trivial impetuses you put down in the initial collection phase, and when you get around to processing them, you have habits that say "do task now if takes less than 5 minutes". GTD is (apparently, I tried to get it working for me but to little success so far) a life changing thing.