I would actually advise against it, or at least take the approach of removing cards that are too easy. I remember reading some article about spending your time learning stuff that is "just hard enough". When you study things that are easy you are kind of wasting time, you want to the material to be +1 in difficulty what you already know, not +0, not +250. While the easy questions give you satisfaction, they aren't helping you actually learn. I would argue that multiple cards on the same subject end up equating to a bunch of time wasting easy cards.

The disclosure to this is that I also don't think you should spend a lot of time figuring out how to create cards. There is some payoff in optimizing the process, but focus on just making the cards and reviewing them so you are learning the actual target subject.

All that said, my current approach is to create cards for concepts that I think are a little hard to understand or that I know I won't see enough repetition in daily work/tasks. If I find out after a few weeks the cards are too easy or too similar I usually with just delete it.