Hi,
I think the bot answered your question!
To add to that, you could also create a filtered deck instead of a new subdeck. The difference is that cards you answer correctly in a filtered deck will return to the main deck, while cards in a subdeck will stay there until you decide to move them manually.
Here’s a tutorial for filtered decks: How to Build a Custom-Filtered Deck
Let me know if there is anything else we can help with! 