"Where does flashcards in a text book fit into this?"
Answering a question doesn't have to rely only on rote memorization. For example, a book might explain how to do addition, and then ask "What is 110+257?". You might need to use a piece of paper to work out the answer. And, if that same question is asked again a couple of weeks later, it's unlikely you'll remember the answer. You'll need to work it out again, reinforcing your understanding of the technique.
"spaced-repetition is far more effective when you create the cards yourself"
Yes, but part of the reason is that there's little point in having a card for something you've not encountered in another context. But Quantum Country doesn't present questions to you until after you've encountered the concept in the text.
Answering a question doesn't have to rely only on rote memorization. For example, a book might explain how to do addition, and then ask "What is 110+257?". You might need to use a piece of paper to work out the answer. And, if that same question is asked again a couple of weeks later, it's unlikely you'll remember the answer. You'll need to work it out again, reinforcing your understanding of the technique.
"spaced-repetition is far more effective when you create the cards yourself"
Yes, but part of the reason is that there's little point in having a card for something you've not encountered in another context. But Quantum Country doesn't present questions to you until after you've encountered the concept in the text.