I usually refer to this effect by noting that "context switching is expensive." I got it from CPU scheduling but it's also famously true of light bulbs: turning it off and then on again costs more energy than leaving it on for a short time. (I forget what the actual time threshold is offhand.) This is why grouping/batching tasks works--if you can do three things in a row in the same place, you don't have to switch contexts for each one. It's also a case against multitasking.

I would add to your hurts/help lists "having an overwhelming quantity of work" and "setting yourself clear, modest goals," respectively. I've been discussing elsewhere the task system I've been using for myself lately; the relevant part is that most of the time I only see my short "today" list of about 5-6 items. I don't even look at the long list of tasks to-do-ever, except when I'm adding something or picking out a few tasks to go on the next day's list.

Another suggestion for the helpful list: "novelty." That's what pulls your attention to google reader, but it's also what makes you feel more organized and productive when you're trying out a new organization system. I wonder if one could use this effect deliberately--change the format or style of your organization/task list periodically, to keep it fresh and interesting.