The more facile you get with the GTD models, the faster you’ll be at processing your input, such as new email. We’ve found it takes most people about 30 seconds to process something. That means making a clear decision about what “done” (the outcome) and the “doing” (the next action) looks like. No software will do that thinking for you—but the GTD models will certainly assist you in improving your efficiency, productivity, and speed in processing.
–David Allen