Unconventional decks like having anki cards for a whole piano piece or problem in a textbook might work

I have used Anki for learning bass guitar parts to songs, and I found this method: break a piece up into individual riffs or themes, make flashcards with the "[name of song] [riff or theme sheet music / tablature]". Add in flashcards that use cloze deletion on a list of how the riffs progress (intro -> verse -> ... -> verse -> chorus -> coda, for example, deleting chorus) and you have 10-20 cards, depending on complexity. I also threw in transitional licks appropriate to the song to bump the count up.

When testing yourself with the deck, have your instrument at hand. On riff cards, practice the riff for five minutes, then hit 'again'. Answer the other cards as normal - I originally planned to play the riff that was deleted, but I found it wasn't really necessary. I suggest responding 'again' to each riff card until you can play the riff first try.

The bonus of this method is it works out to ~1 hour of practice of your instrument. I found huge improvements because it ensured 80% of my hour was spent actually learning and improving rather than practicing well-known or ingrained patterns. My recall of songs from name was significantly higher too.