Comment by marcosdumay

IMO, the most limiting feature is that spaced repetition is a method for memorization, but memorization is only one part of learning and it's very often not the most prevalent part.

But when memorization applies, gamification is a really good way to avoiding burnout (as long as you don't overexpose yourself to it). There are many spaced repetition games for children, I don't know why people make so few of them for adults. (But then, fearing the duolingo owl is a popular meme nowadays.)