This is my point of view - the flashes are because muscles of the eye are contracting the eyes length - thus short term improvement.
What I would expect in long term that the eye will compact so I do not have to use muscles for this (then with 'idle' muscles I could see).
I would ask anybody who succedded if this is the feeling long term (I can see on this forum another thread - "can the eye get shorter" , but without any details how one feels then).
It can be triggered as I understand mostly after blinking or when gazing at the objects. It does not mean that the eye is shorter by itself, but is just contracted by muscles. What we have to pay attention to is to relax ciliary muscle at this time - as sometimes eye starts strething ciliary muscle to see even sharper - but it is a stronger pain in the inside of the eye - like a "needle touches your eyes"). Do you feel any such needles ?
When I look at Snellen I do not get the same good results as looking far away during the walk. When walking I can see distant objects clearly also for longer - like 30 sec , sometimes can reset this with blinking (and feel this push from the back fro the eye), of course when I am walking I do not have Snellen to measure it
1) In other threads you seemed to experiment with other PLUS powers than 1, of course the power required depends how far are you from the screen.
Do you have this effect as mine (I guess it must be common), after wearing PLUS for even a few minutes when I remove it I can see very clear (the eye is set in the "DISTANCE reading" state induced by the lenses). I guess it must be common, but would appreciate your confirmation.
2) I do not think small letters are better to make the training , I agree fully that vision training should be done on letters as they are black and white (easier for the eyes and the person to adjust when contrast is high).
What I prefer to do is to "try to control if the eye's back is compacting. I feel a slight pushing at the back of the eye - are you feeling the same ?
3) when eyes' muscles are having rest for whole night it is easy to guess that it will have strength to compact.
In the morning I can see better without any vitamin - are you sure it is not a coincidence ?
Of course it takes some minutes until after wake up all the eye are 'unglued' and start working in my case.