It would be interesting to add a way to enable flashcards at given day or time, using some kind of calendar feature. At the moment if you disable a flashcard it will not appear in queue till you manually enable it.
Use case: I learn languages, and I make flashcards on basic vocabulary. I can make a lot of flashcards in one day, distributing their appearance in queue by weeks or like that, and then I can just forget about it. Also, queue will not be crowded by too much flashcards, as if I made all of them at the same moment