Yeah, you're probably right. I agree that the problem might be shifting focus every year but the one difference with your math examples is that Singapore Math/Common Core math etc. all seem like different systems that don't build on top of each other. You (I'm assuming here) can't focus on Singapore Math one year, then the next year to add Common Core math on top of that etc. Its one or the other.

Spaced repetition on the other hand is a cross-disciplinary technique that just needs to be introduced and kept there. There's nothing else out there to substitute it with. If the young staff hype it up one year and then it becomes part of the curriculum and then they move on to other fancy edtech things, then there's nothing wrong with it.