Notably, after about 9 months I stopped putting in as much effort though I continued using under-powered lenses. My vision today is -3 (about 5 years after I got it down to -2.25)
If you are curious about the idea, EndMyopia is a pretty great resource. A lot of people are fixed in their ideas in how this all works, so they will dismiss it outright. But if you have nagging doubts about vision science, there are some really interesting alternative ideas out there.
Anecdotally, my wife and I have been following the concepts for about a year and a half. We've both reduced our prescriptions by ~1.00 diopter. If nothing else, it helps you to become much more aware of what you are actually seeing and how variable your vision is from moment to moment.