I just want to point out something in this graph because of the way we’re prioritizing the sums of retrievability scores.
You can see in some of the better performing sorts, there’s a big gap in the middle. That’s because they’re allowing the most forgotten cards to go to the back of the queue. That’s a good thing, but it causes those R scores to drop further and further while they are waiting to be studied. That’s what you want when you are working through a backlog, you don’t want to be wasting efficiency on the most forgotten cards.
This also causes the sum of retrievabilities to look really bad for those sorts. You have a bunch of cards being pushed way down, and other sorts prioritize those cards and make their average R score look higher, even though they’re terribly inefficient.
This is why I’ve been skeptical of total_remembered and seconds_per_remembered_card being useful at all.