A true "master of arms" should be able to effectively carry and deploy ANY common defensive weapon platform
That
sounds good.
And it is true if the carrier is consciously aware of the characteristics. of the firearm.
At the range, he or she is so aware the instant the gun is placed on the bench.
But we are speaking of self defense.
in concealed carry, where the gun is several levels of consciousness below most of that one is doing, one is not always aware of that he has strapped on--unless it is always same gun.
If one carries the same thing every day, it doesn't matter.
If one carries firearms that are very similar, such as different Glocks, it doesn't matter.
But if one carries a Glock on some occasions, a 1911 on others, a gun with a slide-mounted safety in others, and so on, it will matter.
It is not a matter of being a "true master". It's a matter of having to detect what firearm one is carrying when drawing and remembering how that one works.
That's not important at the square range, but in the stressful moment of an SD encounter, it can slow the first shot, or leave the defender wondering why his gun did not fire at all, at a very, very bad time.
That's not untested theory. It can be shown via controlled scientific experiment.
But one need not do that with firearms to know it. The same kinds of tests have been conducted using all kinds of mechanical devices.
These principles influence the design of aircraft displays and controls, of safety cut-off switches, car stuff--you name it
Long ago, they led to the adoption of the PRNDL transmission selector quadrant as the standard on all cars with automatics.
Anyone who has ever studied human factors engineering understands these things. I still remember a good bit of it, many years later.
Some years ago, the president of an aircraft company assumed the position of CEO of an automobile company. He decided to drive every model they made.
When he found that the wiper and washer controls, automatic headlamp switches, instrument panel lighting controls, parking brake controls, and so on differed among models, He found that to be a significant safety issue. It became an agenda item at an executive meeting.
It was not an item for discussion. People left with clear direction.
Some of us who had worked under the man had some fun imagining the nature of the meeting.
Some things are just basic.