I created a test “Smart Rule” and seems to be there for me. I of course may be doing something wrong. I’m good at that. I also might have a setting somewhere that I don’t know about or care to hunt for.
Not to curb your enthusiasm, but there are apps out there for exactly the purpose you have in mind. And they exist already for quite some time. Not only using “space” for repetition, but also “response quality”. Personally, I’d vote against this kind of feature creep in DT and for using dedicated apps.