Well, there’s no right answer. Different folks will have different ideas for the best way to approach this.
I suggest working backwards. What’re you trying to do or achieve with these notes? Pass the course? Carry the knowledge forward? Relate historical study with your developing knowledge of economics?
Based on the goal(s) you decide upon, you can decide what the best model and structure might be. If memorization to pass some exams is key, you might want to make sure it’s easy to study your notes. If I were you, and that was what I was trying to do, I’d probably “note to the test” (as in “teach to the test”). Look up rubrics and exam outlines, create notes about those things, then as you attend lectures and read study material you can align the notes you’re making with the notes you’ve created about what you’re going to be tested on.
A similar approach can be used for assignments and essays, etc.
If you’re building out your notes for a different purpose, then adapt the above to that purpose. Think through and write out what you’re trying to do. By reifying that thinking, you’re creating a “target” to aim for. Then, as you progress through your studies, craft your notes with that in mind.
But—and this is important—don’t get bogged down with trying to have the perfect structure/approach before you start. Instead, address your work with flexibility, and be willing to let your future self see what you did at first as “wrong.” In other words, expect to change your structure as your thinking evolves.
Last thing: don’t worry too much about what a note is.
Should a lecture be a note? Yes. What about an event? Yes. Sub-topic? Yes.
A single note file is just a place to put something under a label. So is a heading, and so is a vault. So it’s sorta fractal. The more you break things down, the more you’re able to collate and relate the different nodes of thought you’re instantiating in your vault. But that takes time and energy.
So, instead of stressing, do what feels natural, and be willing to go back and change the things you wrote before.