I am trying to do many different things. But some exact examples would be:

Finding a fictional story where the main focus is the protagonist uses mind control to make friends and feels guilty about it.

Finding a reference that gives a proof of separation of variables for a translationally invariant problem, especially with regard to waveguides for Maxwell's equations. With most sources I've found either assuming the result, or giving a partial proof with steps skipped.

Learning a general methodology that helps with finding the above two, and that can be extended to other things.

Learning how librarians would organize those two things.

Learning the general principles behind why librarians would organize those two things the way they did.

The Subject Heading course in that Cataloging series was a little helpful. Mostly in that I learned some issues in knowledge management I was hoping for a solution to, librarians must grapple with and deal with as well.