After WW2, Canadian Inuits started to send their children to school for the first time in history and myopia became endemic from that generation onwards.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1956268/
And to put the source in context:
- This was before the age of computers and smartphones so screen time was much less of a factor.
- Inuits traditionally spend a disproportionate time indoors due to the climate.
- The schooling was likely shorter and less stressful than those found in places like Japan and Korea, yet the effects are just as apparent.
Similar rises in myopia rate was observed when daily schooling was introduced to many other places, but few occur on the same scale. Thus it is possible that Asians and Inuits are genetically predisposed to myopia and it took until the modern age for this to become a problem.
Your idea about allowing the eye to "rest" is not new and it has been the subject of several large scale clinical trials such as the COMET study linked below. In short, under correcting myopia does help to slow down progression. However, the benefit is too small to justify not fully correcting vision which will result in a better quality of life.
https://pubmed.ncbi.nlm.nih.gov/11578789/