I would disagree :) I think the main idea of SuperMemo (now) is actually incremental reading: https://supermemo.guru/wiki/Incremental_reading https://supermemo.

I would disagree :) I think the main idea of SuperMemo (now) is actually incremental reading: https://supermemo.guru/wiki/Incremental_reading https://supermemo.guru/wiki/Incremental_reading though it is nowhere near as popular as spaced repetition. I think we'll see more alternate implementations of IR pop up over the next few years.