I've had GTD partially implemented for about three years now. As is true with others who've posted to this forum, I have Attention Deficit Disorder. I'd love to get some feedback from folks on where GTD works for me at where GTD (or perhaps my current understanding of it) breaks down for me.
The Master Task List and the Occasional (should be weekly) Review do an excellent job of reducing my anxiety about forgetting something important. Making sure my next actions ARE next actions addresses my tendency to put stuff off when I'm not sure how to proceed on them -- sometimes my next actions are ridiculously tiny, but that's okay if it gets me off center. Making checklists for repetitive procedures also helps keep me from dithering over the "what's next" issue. My "getting ready for work" checklist probably saves me ten minutes every morning.
Where I'm having my biggest breakdowns lately has to do with selecting my work. Dividing my list by context doesn't help -- 95% of my work time is spent in front of my computer. I just don't have much of the "15 minutes in an airport" kind of time that appears to make the context lists helpful. I do have my lists sorted by "type of work" -- reading, writing, phone calls, etc. -- which helps me select tasks appropriate to the current levels of energy and ability to focus.
In short, my master task list ITSELF is a great source of overwhelm for me. On a good day, I take this in stride. But on a bad day, I can be reduced to a blob of ineffective anxiety by the sheer size of the thing, and about the best I can do is nibble around the edges of it by selecting low stress tasks, like a predator taking down the slowest and weakest prey.
(I did see a suggestion in another thread about the book "The Now Habit", for which I've just placed an order.)