That is an excellent question - because I asked it myself about the Bates' method, and attempted to answer it, not in terms of "medicine" or a "medical-type" answer.
The question becomes, "... I am THINKING of wearing a plus..., and ... how long must I wear the plus ... until I can QUIT wearing the plus...".
That is truly the reason why a plus can never be prescribed for prevention, by any person who is medical. I am not insulting your intelligence with this discussion.
The other issue, is people who "lock" onto a prescription, like they are going to "cure" -1.25 diopters of myopia - and under medical control. I have yet to find anyone who has done that - with the involvement of a medical person.
The realistic question, should be, "... how long must I wear a plus, until I confirm, objectively that I read the 20/40 line, or better....".
The answer to that question is this ... as long as it takes. If you do not want to wear the plus, then, of course do not do it. There is nothing that is casual, or "cure" about the plus.
This is still in the "education" phase for you - which I accept and understand. What convinces me that the plus must be used for the long-term, is the "plus" study, conducted by Dr. Young. I will post that in due course. http://myopiafree.wordpress.com/study/
Prevention is not medicine, and few people will take any time to understand statistics. But the person who chooses to reject any wearing of a plus (and self-snellen check) should actually look at these statistics. (Easy to read.)
Vis 6-17, LLPD. (Readable format). I also posted this as a spread sheet.
If you look, you will find the students, NOT wearing a plus, go down at a rate of 2/3 diopters per year, and then -1/2 diopter per year. In fact, this process continues through college. A person who does not believe this - is kidding himself.
The plus group did not go down. In fact a few went up (very slowly, I agree).
But this study was "forced wearing" of a plus by children who had no idea of what they were doing, how to do it or why they were doing it.
(This is why a child can not be successful with the plus).
But for a person who is old enough (but still at 20/50), I think the results could be different. But this becomes your responsiblity to study and decide.
Of course, Musa, if you find a person advertising you can get out of myopia in two weeks - why not buy their package - and report back on your results?
Of course, if this product works for you - there would be no further reason to ask any questions on this site. But give it a try.
Thanks for your helpful answer. I know this question does seem quite broad, but how long do you think of wearing the plus do you think it will take for someone to improve their eyesight in my position by .25 D-- for e.g. going from -1.25 to -1.