Have you tried SuperMemo? Intervals matter because they correlate with rep loads. The more accurate the intervals, the lower daily rep loads can be.
The SuperMemo creator has spent 3 decades and collected plenty of data, it's hard to imagine that he wouldn't be able to improve on an algorithm from 1990.
The SuperMemo creator has spent 3 decades and collected plenty of data, it's hard to imagine that he wouldn't be able to improve on an algorithm from 1990.