Are all open loops really created equal?

I'm going to put my question-GTD hat on again.

One premise of GTD is that as far as your mind goes, all open loops are created equal. That is, no matter the time, place, or importance, your mind will focus on an open loop as though it is important, and this is the time and place. Evidently, your mind can't distinguish between loops that it should think about and those that it shouldn't.

Now, is that really true? My experience and vigilant mental observation over the past month has led me to believe that it's not. Big, nasty tasks take up way more mental and emotional energy than little ones. Evidence:

• I simply do not stay up at night wondering whether I will remember to get the butter at the grocery store.
  
• I do not keep thinking about when I'm gonna get the oil changed in my car when I should be paying attention to the conversation I'm having with my friend.
  
• I do not lose focus on large, important tasks because I'm thinking about posting the birthday card on time to my cousin.

I do however, have trouble sleeping if the enormous monster of a task is looming over my head because I didn't get to it because I was too busy tweaking my system, finishing little errand tasks, and doing whatever else I do to procrastinate. This is not to say that you shouldn't keep your capture system pervasive. Little tasks do come up, and yes, they come up at inappropriate times. So a quick, easy, well-reviewed capture system is necessary so that when you've finally gotten to the big nasty task and "get-butter" gets in the way, you can quickly capture it and get back to work within a 10-30 seconds. And that's precisely the point of the capture system, to not give them more than the 30 seconds they're worth. But should you spend time tweaking your processing system for these little tasks? Browsing the internet for hours on the best way to combine lightweight moleskins with tiny pens to capture any last morsel of thought that may come through your head? No. Simply no. Don't waste your time. You know what the important tasks are and your list is overcrowded as it is. Get to doing!

As I previously discussed in Priorities and Getting Things Done, big, large priority tasks are what you should focus on because those are the tasks that get you ahead in your field and get you closer to your higher altitude goals. Here, I want to reassure you that you aren't going against all that is holy in GTD and letting your mind get clogged up with open loops because you're letting some of the little tasks slip in place of the big ones. In my experience, the little tasks barely take up as much space in your head as the big ones do, so why give them more than the 30 seconds they're worth?