It is a good question, and there are various opinions and scientific studies on this very topic (and there’s been quite a deal of research for decades on it). At the end of the day, however, each person essentially needs to determine what feels and works best for them, especially given other constraints like how much time they have to devote to study, as well as their personal aspirations (need to cram for a test or exam? more short term goals? long term goals?). Are you OK with an 80% average retrieval rate over the short term? Or do you need to pass a major examination (cramming for the JLPT or a university test) where you need a higher retrieval rate such as 90%?
Overall, current research seems to confirm that the best time to practice retrieving something from memory is when you are on the verge of forgetting it. It’s optimizing for this point that is not only most time-efficient for studies, but also allows you to solidify the memory long term.
I am also curious as to the inner workings of Bunpro’s SRS system. I think if you get something incorrect as new information, you should cram or drill it at least once or twice until you are sure you know it fairly well in the short term. Then you can wait until the end of the day or the next day to click on review.
The most important thing to remember, imho, is that more frequent studying/drilling of the same concept can actually be counterproductive to memory stability. More does not always equal better when it comes to how the brain commits things to memory.
Lastly, when studying similar grammar points, be careful to not overload with too many similar points all at once.
