It's theoretically possible to 'skip' a MUST task by marking it done and then manually re-adding it to the list. Because that's a (comparative) hassle, it introduces a psychological barrier that will keep most people from doing it to 'cheat' (the equivalent of channel surfing), and will make them only skip a MUST item when absolutely necessary.

There should be a button that lets you pause a particular task from being selected next. I think it would jive with the minimal approach