Thinking about these questions brought up another, related issue.
My own experience with red dots included a period of time where we were working with the red dots for training and development but still carrying irons on duty. My personal experience was I had little to no difficulty switching back-and-forth between irons and red dot. However, among skilled shooters in both my own agency and other agencies we work with some people were able to shift back-and-forth easily and some people could not despite being competent with both sighting systems. They would require a period to re-acclimatize themselves to one sighting system or the other.
I initially thought this might be an “everybody’s eyes are different” issue but this seemed less common with new shooters who started on the dot. That raises the question of whether this is an eye issue or a mental / programming issue. And if it’s not a congenital eye issue then is it residual to the experienced shooters being “wired” to hard front sight focus ?
This question has me wanting to pull up and go through Gabe White’s old PF postings on vision and visual accommodation.