Southnarc’s observation re: steering irons is accurate (at least for experienced irons shooters) but context determines if it is a feature or a bug.
Peripheral” vision is not just on the left and right, we also have upper and lower peripheral vision.
Many experienced irons shooters do not realize how much they “steer” the sights in their lower peripheral vision as the present the gun during a “normal” presentation and how much of what they think is their index is actually steering via their lower peripheral vision. They’re subconsciously seeing the top of the gun in their lower peripheral and starting to align the front and rear sights from the top view.
These are the same shooters who have issues “finding the dot” when they try optics without any formal instruction.
These are also the same shooters who, if they persist or take the shortcut of formal instruction in use of the dot to the point they start consistently seeing the dot during normal presentations, suddenly find their irons only presentations are now noticeably faster and more consistent than they were before.
In awkward positions lower peripheral steering can be a feature but in most circumstances it’s a bug. During normal presentations it’s inefficient and slow.
“Good” irons shooters who already have a good index have minimal issues finding the dot during normal presentations. Some of the poo-pooing of dots is from people whose ego is bruised when they learn their index is not as good as they thought it was. IME there is often a correlation between those who poo-poo dots and those who poo-poo timers.
It would be interesting to do an experiment and see if optics with an alignment aid visible from the top, like a paint marker line or other feature aided in lower peripheral steering in awkward positions. My own favorite pistol optic, the SRO has such a line built into the top of the housing and marking such lines on top of RMRs and DPPs was common in the early days of dot use.
Also what effect do BUIS (or lack there of) have in the same circumstances?