With regard to the challenges in approaching a project that begins with "Learn..." or "Read..." via GTD methodology, if I may venture a thought here, I think maybe your learning project has a next action (or a sub-project) related to identifying ways to learn the subject matter that could work for you. Then you could determine the contexts they fit in. "Read____" or "Learn..." in itself may just not be do-able at this stage of the game. To get there, the first actionable step might be any of the following: "identify times and places where I can read this type of material", or "examine the book's table of contents to find relevant chapters" or "brainstorm with self or friendly expert the questions I want to be able to answer" . Or, the Next Action might be to list the external stumbling blocks or my gut-level objections to doing this "Learning Project" so far defined. I have noticed that I avoid getting started on projects in which the scope is too large, or the context and the next action are either ill-matched or even confused, or the proposed method cannot support the identified outcome until some pre-requisite actions are taken.