On the topic of SR specifically, what does it mean to be best in class? I am just a layperson who uses a SR tool or two and has a passing interest in the topic,

On the topic of SR specifically, what does it mean to be best in class? I am just a layperson who uses a SR tool or two and has a passing interest in the topic, but the Wikipedia article on SR gives the impression that there are a variety of algorithms out there and none are established by research to be definitively better than the others, in fact the Criticism section mentions a study which found that absolute spacing was just as good. https://en.wikipedia.org/wiki/Spaced_repetition#Research_and_application https://en.wikipedia.org/wiki/Spaced_repetition#Research_and... The OP said he's using Ebbinghaus' "forgetting curve" which is not exactly a SR algorithm but something similar, there is an actual formula associated with it - https://en.wikipedia.org/wiki/Forgetting_curve https://en.wikipedia.org/wiki/Forgetting_curve