So in 1988 the research was robust, plentiful, and clear. What happened since?<p>I went threw primary, secondary, and tertiary education between 1998 and 2018. If there was any use of spaced repetition in my education it was not apparent to me. It was never recommended to me as a study technique, even though 'flashcard study' was recommended often.<p>The 9 impediments discussed are not considered strong enough to be "discouraging", but 30 years later spaced repetition isn't part of standard western pedagogy and it has no significant mindshare. The only place it seems to have decent uptake amongst students is in Medical school.