I've heard other people mention this approvingly, but I don't know if the actually did it. It's on my list of things to try at some point, though.

This is probably what you meant, but it might be more productive (and slightly less Hard Mode) to be able to choose "do immediately, do never, or break up into subtasks" while you're actually going through the list.

Also, there are some tasks that I actually do want to postpone because they're not my comparative advantage (for example, it's raining right now, so I want to postpone errands until later tonight when it stops). That's prone to rationalization, so I'm not sure how a system could handle that, but it's something to think about.