I think there is evidence on the PVS forum I linked to, even for the eyeball actually changing shape after doing those exercises longterm, despite what is believed by the majority that once the eyeball elongates - it can't go back. Think of it this way - when people become long-sighted, the eyeball shortens. There is no set point at which the eyeball can't shorten. The theory that the eyeball can't shorten once you are even slightly Myopic - does not make sense.
I've personally had no success with pinhole glasses or the Bates method. I think there have been studies on both proving they don't work, but I'm not sure who carried them out. Obviously if the people selling glasses funded the studies then I'm doubtful to trust them. I'm still in the early stages of the Power Vision System so I don't know about that one yet, but there are a great number of positive results on the PVS forum. If I do improve my eyesight even a little, it may take a few months, but I will post it here.
Taking regular breaks is a good thing, yes. Lots of close-up work though increases eyestrain and eventually increases Myopia, so what you really need to do is halt the process by wearing reading glasses as they focus your eyes more into the distance, thereby reducing eyestrain. Note that most Opticians never really tell you this. Even though I have high Myopia, and even when it was rapidly increasing, I was never told reading glasses were a good way to stop it getting worse. In fact, when I told them I wore reading glasses they actually said to me that I didn't need to do that. BUT, wearing reading glasses immediately stopped my Myopia getting worse. I've been the same prescription now for several years. It is very well known by Optometrists (or the ones worth their salt) that reading glasses help Myopics.
I hope that helps. In my experience, a lot of new theories are torn to shreds before they're given any credibility, and the subject of eyesight has bothered me for most of my life, especially as my eyesight never needed to be as bad as it is today, just because I've never been told for instance, that wearing your prescription for Myopia while doing close-up work makes eyestrain much worse.