Hi Giacomo, I am sorry to hear it did not work out for you and it is great that you can share your experience with others. As much as I love spaced repetition, and as much as I continue to use it on a daily basis for years with great result, I would need to (unfortunately) agree with you on this one.

In college, spaced repetition helped me get ahead, but it felt nearly impossible to convince my peers of this. While I was able to effortlessly remember thousands of vocabulary words in my language program, my peers struggled and failed to heed the simple advice of "just put it into Anki". Spaced repetition is valuable, but much like having a good diet or exercising regularly, it is really really hard to convince people of the benefits. A spaced repetition SaaS can easily become akin to an unused (and eventually cancelled) gym membership.

It seems that most of the apps that make it in this space ultimately need to compromise on their fundamentals in order to get traction. I don't need to name any names here, there are plenty of examples of SRS apps that started as solid tools for learning but evolved down a path of gamification to a point of diminished usefulness.

Anyway, sorry again to hear about this one and best of luck to you on whatever you decide to build next. Like you, I am continuing work on my (noncommercial) SRS and I always enjoy hearing your perspectives. Feel free to reach out if you ever want to bounce ideas around.

I have been using Supermemo daily for almost 20 years, and I have basically stopped trying to sell people on the idea. When I explain it to them, they agree that it is a good idea, but very a few people can truly follow through in the long-term. Yes, SRS is basically a gym membership that most people will stop using after Jan 3, I like that metaphor.