That depends obviously on the skills of the individual.
I think giving someone the Mnemosyne database to analyse for better ways to predict Spaced Repetition System learning would be useful if that person has enough skills to do genuine work. Gwern works to bring that data into a nicely downloadable format: https://archive.org/details/20140127MnemosynelogsAll.db
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
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