> I think if you walk into the bottom 80% of classrooms you would not see, interleaving, spaced repetition, recall-over-reread, or topic shuffling to avoid interference.

Where have you taught? I taught in Australia and the United Kingdom, where many of these things were mandated by the promulgation of spiral curricula by the relevant government departments. I'm aware in the US that, for example, algebra is taught as one or two block courses, but in the school systems I've taught in, algebra is taught as a few 'topics' of about a month in duration each, sprinkled throughout the whole four or five years in which mathematics is mandatory in secondary school. For Year 7 to 10 in Australia, there would be one or two topics for each of physics, chemistry, biology and earth sciences, covered across each year, building up from year to year. None of this was a choice by individual teachers or even schools; it was an artefact of the way the curricula are structured.

I'd be curious to see how this is laid out in plan view. Are there any resources you can recommend on this topic?

Right, that specific claim should be understood with US high schools and higher education in mind. There the massed approach rules the day.

Since these things I mentioned are well demonstrated to be effective and you don't think there's anything left to be had with a subject-agnostic approach, I infer you have a high opinion of how well these countries have implemented these "tactics". Is that right?