Anki, is by far the most popular "spaced repetition tool" to enable long term retention of learned material in 2021.
It does so using a scheduling algorithm which prompts the user to recall a piece of information at the time of optimal "desirable difficulty."
In this fashion, it enables large amounts of information to be memorized (e.g. Pali language, Buddhist lists, Suttas, etc) with the optimal return on investment of time and energy.
One advantage to having this information committed to memory, as the monks of 2500 years ago did, is that it can be instantly recalled and used in reasoning. In this fashion, memorization creates the conditions whereby deeper insights into the truth of existence can be extracted more quickly.
I have a strong intuition that this might be part of the reason why arahats were more common at the time of the Buddha than they seem to be today. For this reason, I strongly suspect that spaced repetition practice would be helpful for those intent on mastering the skill of nibbana.
I know that many Buddhists use this tool and that many shared decks exist. However, I have not been able to find any listing of Anki decks for Buddhism thus far. Where are the most common places to find Pali/Buddhism Anki decks in 2021?