Excellent explanation Gardener, I agree 100%.
I think that each of us has things where we are a little at a loss, and other things we can do in our sleep, just depends on our specific work experience. If you are asked to do something the 50th time you likely don't need to spend a lot of time deciding how to set it up. The first time you do.
And if you are in the early stages of your GTD system, everything takes on a small but extra learning curve as you try to understand how it fits into the process with everything else.