I'm not certain that the research on forgetting curves has nailed down the timelines well. I know the Supermemo creator thinks his algorithm is best, but I susp

I'm not certain that the research on forgetting curves has nailed down the timelines well. I know the Supermemo creator thinks his algorithm is best, but I suspect there's a lot of wiggle room and individual differences. Who besides Ebbinghaus has published rigorously on it?