> When you first start to use GTD you should take an hour to write down all things you want to—or have to—do.
An hour is not even close to being enough. A whole weekend may get you to 50%.
> If it’s something that you want to remind yourself about later (“I really didn’t understand this article, I should have a look at it again in two weeks”) it should go into your calendar or your tickler file
The problem is that my tickler files become bloated with these, and it becomes a daily burden to open that day's file and try to decide. If I deferred something till later "because I couldn't decide what to do with it", there's a 90% chance I'll defer it again. These are items I want to work on actively, and not put in the Someday/Maybe list.
> This is where the some day/maybe list comes it. ... This list should be reviewed weekly along with the rest of the system as described in the weekly review section below.
Perhaps many people don't have as much aspiration (or imagination), but my Someday/Maybe list is huge - hundreds of potential TODOs/projects. Reviewing that every week is a huge burden, so it's not done. I treat Someday/Maybe almost as a garbage dump - I don't look at it, but my brain takes comfort that I've captured it somewhere.
It's got to the point that I now have an "intermediate" list in between my active and someday/maybe. This list contains items I must do, but I've placed them there because I lack the bandwidth. Whenever I finish a project, I move items from this list to the "Active" list. I need this intermediate list because I know once something goes to Someday/Maybe, it's practically lost in all the noise.
One of the problems with GTD is it doesn't address how to focus or prioritize, nor what to ask yourself during the review. I've found making a Do Not Do list to be far more effective (as in, at the beginning of the year, I list projects that I commit to not doing until I'm done with the ones I do want to do). Listing goals for the year and asking myself weekly/monthly what work I did not tied to those goals is helpful during the review.