Welcome to this forum, Mercurial. I like your screen name.
...I'm concerned that I might be wasting my time due to misunderstandings of details about the method.
First, the eyesight page talks about periodically pushing the object of attention outside of focal range and waiting for it to clear up again. I'm very unsure about the rhythm of this. Am I supposed to keep it in that strained range for the 1-3 hours of training? Am I supposed to wait until it clears and then immediately bring it back into comfortable range? Or is it something in between (e.g., hold it in the effortful range for ten seconds and then rest for ten seconds)? Or have I completely misunderstood and it's something else entirely?
There is no magic rhythm that is optimal for everyone. The key is to push yourself to the point of discomfort, but never pain or strain. Some people might need to oscillated between D1 (perfect focus) and D2 (edge of blur) every minute or two. Others might be able to "hang out at D2" for 15-30 minutes without a break. This is more of an art than a science. Play with different rhythms and find what allows you to make progress without pain.
In this respect, print pushing is like weight lifting. Ask ten weightlifters what is the optimum number of reps and sets per session, and how much rest is needed. You'll get ten different answers. But any routine that pushes you to make progress without overtraining and injury is beneficial.
Second, there are two areas that are "just outside of focal range" for me, and I'm not entirely sure which one is intended. I can push a book out of range so that it's just ever-so-barely out of focus and make my eyes adjust to that so that it's totally crisp again, or I can push the book far enough away that it's hard to read the words at all and I make my eyes adjust until I can read again. Since the goal is to improve crispness of eyesight, I had been assuming that the former is what's intended. Yet advice like driving without glasses makes me think that we can't be talking about just pushing the boundary of the 100% clarity zone here. There's no way I'm getting my eyes to focus crystal-clear on something that's more than two feet away from my head! But I can get them to focus well enough that I can tell what shape the sign a half-mile away is, or to count the power lines overhead. (Counting lines like that is a bit extra-challenging since I seem to have astigmatism.)
For actively working on your eyes, you want to stay between D1 and D2. That means you can't apply the method while looking at distant signs with edge blur. However, that doesn't mean that looking at distant signs or power lines that have some blur is without value! Any distance viewing helps, even if you can't perfectly resolve edges. In fact, sometimes if the light is bright enough and you allow your eyes to relax, you'll be lucky enough to get crisp flashes or periods of good focus. Sometimes this occurs as "double vision" superimposing a crisp edge or line over a blur. I think all of that is beneficial, but it is not a systematic exercise like print pushing at the edge of blur.
Analogously, disciplined weight-lifting to the edge of failure may be the fastest, most predictable way to gain muscular strength, but that doesn't mean you should shun carrying heavy objects, rock climbing and cycling up hills as alternative "natural" ways to get stronger.
Probably some combination of intense focused exercises and natural exertion is best in ANY field of strengthening or rehabilitation, whether that be for muscles, eyes, or even the brain!