Some people criticize flashcards as optimizing for rote memorization and deemphasizing understanding, but you'll never achieve understanding or mastery in general without a solid platform of knowledge to work from.
Spaced repetition is an effective way to review things but its biggest benefit is a process that's easy to be consistent with.
Somebody else can have equal or better performance with other technique but just like dieting, it doesnt matter as much what method you use as long as you stick with it.
I also find my verbal fluency is directly affected by how much pure social time I have in my schedule. It makes me think its one of those 'use it or lose it' things and that I need to schedule more time with people.
What do you do for topics like chess?
- Checkmates-in-one - Checkmates-in-two - Defensive technique (avoid checkmate/material loss) - Winning material - Endgame patterns - etc (~5 more)
... That I got by scraping the Lichess database, favoring common patterns that appear within +- 600 of my current Elo.
From there, I have Claude build me a script to convert each of those positions into a .png, then create me a deck with all the cards, et voilà. The front of the card is the position, the back is the best move in that position with a small explanation.
Every ~2-3 months when I see that most of the cards have matured (according the the Anki spaced repetition scheduler, I build a new deck around my new Elo.
I also play a lot. Prior to ~1000 rating I got away with spending 90% of my time in Anki and 10% playing online games, but lately it's been pretty 50/50. In higher ratings, playing real games tends to translate into wins more effectively for me.
For studying openings, it's almost the same thing, but the back of each card is the book move for my opening + the name of the opening the opponent chose.