Like the author said, understanding the card you're writing in your deck is fundamental. In my case, I would add, this is even true of when you add language cards. For example, I once added the word `thwart`. This card doesn't "cleanly" translate to my native tongue, and I was failing it at all times, I was confusing it with other words such as stifle, stymie etc because have a close meaning but not quite the one in thwart. Only after I grasped the exact definition and usage of it I started to not block on it anymore. I now attempt to be better at it by trying to also recall or make up the antonym of a certain word.
Also I started to create decks for:
1. Emacs commands, including custom shortcut which I use daily, or trying to drill new commands or features that I leant.
2. passages from books I read, mostly for those I use cloze deletions.
3. simple arithmetic, in order to be quicker at doing those without having to use a calculator at all times with me
4. shell commands, for example less frequently used git commands, grep or rg options.
A final note on using LLMs for flashcard creation. Sometimes the LLM can come up with some useful examples, or memory hooks, which help in retaining the information. Yes, I agree here with the author: out of 10 cards created with the LLM you're probably going to retain just one, and even that one will need rewriting.