Spaced repetition scheduling and categorization

Should I consider the subject matter of a flashcard explicitly when scheduling reviews? On the one hand, more information is often better when determining a scheduling interval; on the other hand, we want to avoid complexity and overfitting, and one might reasonably hope my category-by-category differences to be captured in my performance itself, without needing to look at categories explicitly. I'm approaching a million flashcard reviews and have never used category data in a scheduling algorithm. In that time, I've made a lot of flashcards about movies.1 Here is my performance in two common response-pattern situations, split between questions about movies and questions not about movies. First, when I make a card and get the first review correct, here's my performance on the second review: And when I get my first two reviews correct, here's my performance on the third review: Some notes and caveats: These are just some high-volume patterns I checked; if you think there's some other…