Make your own cards and quiz yourself. Cards you know come back less often. Cards you miss come back tomorrow.
This is an example deck. Try a few cards, or change it to make it yours.
Every card starts in Box 1. When you get a card right, it moves up one box and waits longer before it comes back. When you miss one, it goes back to Box 1 and comes back tomorrow. So you spend your time on the cards you don't know yet.