"Landauer and Bjork were looking for the optimal moment to rehearse something so that it would later be remembered. Their results were impressive: The best time to study something is at the moment you are about to forget it. And yet — as Neisser might have predicted — that insight was useless in the real world. Determining the precise moment of forgetting is essentially impossible in day-to-day life.
Obviously, computers were the answer, and the idea of using them was occasionally suggested, starting in the 1960s. But except for experimental software, nothing was built. The psychologists were interested mainly in theories and models. The teachers were interested in immediate signs of success. The students were cramming to pass their exams. The payoff for genuine progress was somehow too abstract, too delayed, to feed back into the system in a useful way. What was needed was not an academic psychologist but a tinkerer, somebody with a lot of time on his hands, a talent for mathematics, and a strangely literal temperament that made him think he should actually recall the things he learned." - Gary Wolf in Want to Remember Everything You'll Ever Learn? Surrender to This Algorithm