Just as a matter context, Piotr Wozniak is the author of SuperMemo, the first significant spaced repetition software (SRS) application.  The SuperMemo2 (usually referred to as SM2), devised by Piotr, is used in most SRS software including Anki (arguably the most popular free software SRS app).  My understanding is that Piotr obtained a PhD for his work on these algorithms.  SuperMemo was a commercial enterprise, but I seem to remember there was some falling out with the business side of things and Piotr left (though I haven&#x27;t really followed supermemo for a decade and things may have changed).<p>Piotr has some interesting ideas.  His writings tend to be very much like this article -- bury you in details, some of which you wonder about the relevance.  He is a fairly intuitive in his approach and is very much convinced about the conclusions he reaches.  He always has a large amount of data to support his conclusions, but a criticism I&#x27;ve had in the past is that the data is not always free of bias.<p>I only mention this as there was some suggestion that the submission was a disguised ad.  Even though I don&#x27;t agree with everything that Piotr writes, one can&#x27;t deny that his ideas have helped a lot of people.  He has always been very generous with his ideas and his data.  His business partner was not quite so generous and I believe this was one of the reasons for the fallout.  Whatever you think about the content of this article, my personal feeling is that you can be sure that it was written with the intent of helping people better themselves and no other motives.