Although I can see the reasoning, this absolutely does not work for me. The times procrastination bothers me is exactly in those cases: when there is something important but not exactly specified at the top of the list. I'll feel guilty about not working on it and then end up in a sort of limbo between the task I could be doing and the 'important' one.

What helps for me is exactly the opposite: deciding this important task does not have a clear path forward and therefore go write down each and every question I have about it and need answered before moving forward or explicitly decide I don't have the proper energy/focus for it at that time and move on to something easier.