The SM algorithms, trying to predict the perfect time for reviewing a question, seem like overengineering to me (and also not very well supported by research afaik - we have evidence that repetitions help, but much less what the perfect spacing is). Just randomly sample questions with probabilities proportional to how 'urgently' you need to see them, seems like the most intuitive approach to me. No daily quotas, no running out of questions, just do a few when you feel like it and don't worry about whether you're doing too much or too little repetition.

Is there an app/plugin that works like that? I know you could use Anki like that by just not worrying about the backlog, but in my experience it doesn't work like that.