I have been sharing the GTD ideas with members of faculty at the University I work at.
A common complaint I get is that the longer-term writing and/or research projects they have cannot be broken down to short, simple next actions.
Their challenge is that it often takes 30 minutes-1 hour just to get their head back into a place that their writing can flow. That means that many of their next actions boil down to "Spend Three Hours writing". A the frustration they have is that they have a difficult time finding a 3 hour block to write.