I think there was a study omparing watching an educational video in 1x speed and watching it two times back to back in 2x speed equating the time spent on the material, which found the second group faired better.
Though it's not the question I asked. Would the second group fair somewhere close to the first if it only had listened once?
(I don't buy the argument that this would not be fair since they would use the extea time to watch more stuff ... because that's rarely what people do with their extra time. Especially not watching the same thing again.)
