Seven Years of Spaced Repetition Software in the Classroom

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This is: Seven Years of Spaced Repetition Software in the Classroom, published by tanagrabeast on the LESSWRONG.
Description
This is a reflective essay and report on my experiences using Spaced Repetition Software (SRS) in an American high school classroom. It follows my 2015 and 2016 posts on the same topic.
Because I value concise summaries in non-fiction, I provide one immediately below. However, I also believe in the power of narrative, in carefully unfolding a story so as to maximize reader engagement and impact. As I have applied such narrative considerations in writing this post, I consider the following summary to be a spoiler.
I’ll let you decide what to do with that information.
Summary (spoilers)
My earlier push for classroom SRS solutions was driven by a belief I came to see as fallacious: that forgetting is the undoing of learning. This epistemic shift drove me to abandon designs for a custom app that would have integrated whole-class and individual SRS functions.
While I still see value in classroom use of Spaced Repetition Software, especially in basic language acquisition, I have greatly reduced its use in my own classes.
In my third year of experiments (2016-17), I used a windfall of classroom computers to give students supervised time to independently study using an SRS app with individual profiles. I found longer-term average performance to be slightly worse than under the whole-class group study model, though students of high intelligence and motivation saw slight improvements.
Intro and response to Piotr Woźniak
I have recently received a number of requests to revisit the topic of classroom SRS after years of silence on the subject. Understandably, the term “postmortem” has come up more than once. Did I hit a dead end? Do I still use it?
Also, I was informed that SRS founding father Piotr Woźniak recently added a page to his SuperMemo wiki in which he quoted me at length and claimed that SRS doesn’t belong in the classroom.
Well, I don’t have much in the way of rebuttal, because Woźniak’s main goal with the page seems to be to use my experience as ammunition against the perpetuation of school-as-we-know-it, which seems like a worthy crusade. He introduces my earlier classroom SRS posts by saying, “This teacher could write the same articles with the same conclusions. Only the terminology would differ.” I’ll take that as high praise.
If I were to quibble, it would be with the part shortly after this, where he says:
The entire analysis is made with an important assumption: "school is good, school is inevitable, and school is here to stay, so we better learn to live with it".
Inevitable? Maybe. Here to stay? Realistically, yes. But good? At best, I might describe our educational system as an “inadequate equilibrium”. At worst? A pit so deep we still don’t know what’s at the bottom, except that it eats souls.
Other than that, let me reiterate my long-running agreement with Woźniak that SRS is best when used by a self-motivated individual, and that my classroom antics are an ugly hack around the fact that self-motivation is a rare element this deep in the mines.
Anyone who can show us a way out will have my attention. In the meantime, I’ll do my best to keep a light on.
Prologue
At the end of my 2016 post, I teased a peek at a classroom SRS+ app I was preparing to build. It would have married whole-class and individual study functions with some other clever features to reduce teacher workload.
I had a 10k word document in hand: a mix of rationale, feature descriptions, and hypothetical “user stories”. I wasn’t looking for funding or a co-founder, just some technical suggestions and moral support. I would have been my own first user, and I had to keep my day job for that anyway.
But each time I read my draft, I had this growing, sickening sense that I was lying ...