" The dynamics of these five stages need to be understood, and good techniques and tools implemented to facilitate their functioning at an optimal level. I have found it very helpful, if not essential, to separate these stages as I move through my day. There are times when I want only to collect input and not decide what to do with it yet. At other times I may just want to process my notes from a meeting. Or I may have just returned from a big trip and need to distribute and organize what I collected and processed on the road. Then there are times when I want to review the whole inventory of my work, or some portion of it. And obviously a lot of my time is spent merely doing something that I need to get done. "

― David Allen , Getting Things Done: The Art of Stress-Free Productivity