You can use them for practicing techniques. Have cards which say: use X technique today. You need to actually do that rather than spend 1 minute thinking about it. Which is suprisingly hard. I suspect it works much better if you have some system to guide you in generating new ideas e.g. Zettlekasten. I suspect it could be even better if the method was incorporated into the software itself. Maybe create links between cards as well, and have some repititions where you explore the graph surrounding a card?
I’m also unsure if the spaced repition timings are optimal for drilling techniques. Does anyone know the relevant literature?
Yes that does sound like a promising system for retaining useful techniques. Will try it out.