First, thanks to everyone who regularly posts here -- reading over your ideas and experiences with GTD has helped me move from owning the book to actually implementing the system for myself.
So far I've captured my stuff, generated a list of projects, and have identified next actions for each of them. I have the na's printed out on context-specific lists (@e-mail, @agendas, etc.) in my organizer. I also have a separate page for each project to jot down notes, longer term na's, ideas, etc.
But now I see chaos coming. Some of these na's will be pretty easy to churn through -- I can see getting the e-mails all done this afternoon, for example, which will effectively constitute "progress" on 5 or 6 projects.
How often do you go back to review at the project level to make sure you keep generating new next actions in order to keep the lists current and projects moving ahead?
Thanks for any advice you can offer. I've checked the book, but all I can find that seems relevant is the weekly review, and for some projects once a week seems too infrequent.