When you have an action item on a project list that you know will take a chunk of time, for example...purge general files (2hrs), do you write it on your action list and then schedule it onto your calendar or during your weekly review of projects, do you just place it on the calendar for the date/time you want to do it and not write it on the action list?

In other words is GTD like a funnel going from Project List, to action list, to calendar or does it go from project list to calendar and bypass action list?