Micreconomics: Supply and demand curves versus adverse selection
This example makes me think that there's an underrated distinction between what's most useful for a future specialist and what's most useful for someone who's taking the course and will not pursue further study. If you're studying to be an economist, understanding supply and demand is several magnitudes more important than understanding adverse selection. You can be an okay economist with a mediocre understanding of adverse selection, but if you don't understand supply and demand, you have no chance. But if you're going into some other field, it's probably more important to understand adverse selection. In an ideal world, "economics for non-economists" would be separate from "economics for future economists". I imagine something similar holds true for other areas of study.
Most of these are not exclusive - if you're interested in the topic (for whatever reasons), you should learn both simultaneously (or rather, alternating topics in increasing depth, in intertwined segments such that insights into one area apply to the other).
People who're engaging in learning partly or wholly for the explicit purpose of human capital need to be strategic about their learning choices. Only some subjects develop human capital useful to the person's goals. Within each subject, only some subtopics develop useful human capital. Even within a particular course, the material covered in some weeks could be highly relevant, and the material covered in other weeks need to be relevant. Therefore, learners need to be discerning in figuring out what material to focus their learning effort on and what material to just skim, or even ignore.
Such discernment is most relevant for self-learners who are unconstrained by formal mastery requirements of courses. Self-learners may of course be motivated by many concerns other than human capital acquisition. In particular, they may be learning for pure consumptive reasons, or to signal their smarts to friends. But at any rate, they have more flexibility than people in courses and therefore they can gain more from better discernment.
Those who're taking courses primarily for signaling purposes need to acquire sufficient mastery to attain their desired grade, but even here, they have considerable flexibility:
What self-learners and people with some flexibility in a formal learning situation need is what I call utilitarian discernment: the ability to figure out what stuff to concentrate on. Ideally, they should be able to figure this out relatively easily:
The above work better than nothing, but I think they still leave a lot to be desired. Some obvious pitfalls:
In light of these pitfalls, I'm interested in developing general guidelines for improving one's utilitarian discernment. For this purpose, I list some example head-to-head contest questions. I'd like it if commenters indicated a clear choice of winner for each head-to-head contest (you don't have to indicate a choice of winner for every one, but I would prefer a clear choice rather than lots of branch cases within each contest), then explained their reasoning and how somebody without an inside view or relevant expertise could have come to the same conclusion. For some of the choices I've listed, I think the winner should be clear, whereas for others, the contest is closer. Note that the numbering in this list is independent of the preceding numbering.
PS: The examples chosen here are all standard topics in the sciences and social sciences ranging from middle school to early college, but my question is more general. I didn't have enough domain knowledge to come up with quick examples of self-learning head-to-head contests for other domains or for learning at other stages of life, but feel free to discuss these in the comments.