I've been using the GTD system for over a year now with great results. But one thing I'm uncertain about is how to efficiently keep my Next Actions list synched with my Projects list, such that each project has at least one associated next action. Since it appears that the GTD system recommends keeping these as two separate lists (so the next actions can be sorted by context), how does one efficiently identify which projects need next actions and update the next actions list?
For example, I normally have 70+ projects and 100+ next actions. I keep these in digital lists on my PC. As I complete actions and projects, I delete them from the appropriate lists. When I do my weekly review, I may have 5-10 fewer projects and 30-50 fewer Next Actions than when I began the week. If all I see is a list of projects and a list of next actions, it takes me a long time to figure out which projects need new actions to be identified and which are already current. In other words... how does one efficiently resynch the Next Actions list with the Projects list? And is this supposed to be done daily, or can it simply be done at the weekly review?
Might it be a mistake to even let these two lists get out of synch at all? Whenever I complete a next action for a particular product, should I immediately decide on a new next action and add it to the Next Actions list? This would keep the lists constantly synched, but it doesn't feel right to me, as it interrupts the flow of doing the actions with a lot of decision-making that could be deferred and done as a batch. Doing this kind of synching somewhere in the range of once a day to once a week seems like it would be more efficient.
The method I've been using to help me keep these lists synched is to give each project a name. Every item on my Projects list is preceded by its project name, and the same goes for the associated actions on the Next Actions list. So I can quickly scan (or search) to see which projects already have next actions and which need new ones to be identified. When I look at each action, I can immediately recognize its associated project.
Any suggestions/ideas on other approaches to this problem?