I can partly see where you are coming from. I'm a computer programmer and I really struggle to put my programming jobs in my GTD system. It's not a problem for me because as a rule, I don't forget to do these projects. It's interesting that David Allen uses (paraphrased) someone who is paid to just churn out code as someone who doesn't need GTD.
On the other hand, @DIY is a great context for me. It's one that I don't work through much but once I get my toolbox out or my painting gear set up, I want to work through as much as I can