This is right. I tried and gave up on spaced repetition a few years ago. When I tried again a year ago and did more research, I realised my problem on the first

This is right. I tried and gave up on spaced repetition a few years ago. When I tried again a year ago and did more research, I realised my problem on the first attempt was that I made too complicated cards. I went back and dug up some of my more valuable cards from my last attempt, and some of them were so complicated that I had to break them up into 10–15 cards now that I know how to design good cards. That said, I don't think the point is to make them easy. Since you want to aim for a 90-something percent success rate to get the most benefit out of it, too easy will make the going slower. The point is to make them atomic and that usually feels easy, even if you fail 10 % of recall tests.