Noel;100517 said:
If something comes up that can take less than the time it takes to capture, do it.
Definitely; however, the cutoff time (e.g. 2 minutes) should be longer, usually significantly longer, than the time it takes to capture. Capture might take about 10 seconds. David Allen suggests 2 minutes as the usual cutoff, and his reasoning is not just about the time it takes to capture.
If the activity you're interrupting to do the capture is extremely urgent, then the cutoff time might be close to the capture time; for example, if it takes 10 seconds to capture or 12 seconds to actually do the thing you might decide to capture, but if it takes 11 seconds to do the thing you might still just do it. However, normally the cutoff time will be much longer: capture might be 10 seconds and a 2-minute rule may still usually be most appropriate.
David Allen justifies the two minutes on the basis of whether it's worthwhile to capture the item, review it later at least once and perhaps multiple times, perhaps recopy it from one system to another, eventually erase it, etc. Whether this is worthwhile depends on a number of factors. It's not just a simple comparison of whether the total time spent capturing and reviewing the item takes longer than doing it.
Factors one can consider include: what does one gain by delaying? One can gain accomplishing some other, more important things first, and possibly even deciding never to do the captured item as less important. That can be valuable and is an important part of GTD. However, if you already know that the item is sufficiently important in relation to the stuff you usually do that you're just about certain to want to do it, and if what you're doing now anyway is not unusually urgent, then there might be little or no gain there.
There are psychological factors: I found when I started GTD that applying the 2-minute rule made me feel great, as if I'd been freed up and empowered and able to take first steps on a bunch of projects I'd been wanting to do. Adding an item to a list of actions makes the list longer and may add to a psychological burden. GTD is supposed to let you feel stress-free, but some people feel bothered by long lists.
There could be risks: occasionally I can't read my own handwriting or decypher my own wording. I lose a small number of items, and for some others I spend time figuring out what they are. At the time I figure "I'll understand this", but later I'm in a different frame of mind. One could also misplace a notebook or run out of batteries on an electronic gadget.
You're going to eventually do the thing anyway and it will take as long as it takes, so the choice is not "do this or capture it"; the choice is "do it now, or capture it and also review it and do it later", which takes more total time. The added time is not automatically justified just because it's slightly less than double the time it would have taken anyway. It has to be justified by actual added value due to doing other more important things first. In most cases, I believe, the capture time would have to be a small fraction of the doing time in order to justify capture rather than immediate doing.
