I'm going to agree with FQ. The novice shooter that goes to the range two/three times a year, shoots his groups and is not interested in pursuing anything more, is leaving his proficiency in his hands. Especially, in a SD situation.
A frequent range shooter, practices dry fire drills, and holstering, and drawing, studies, reads, pays to get additional training, has a greater mental, and physical advantage. In some respects, competitive shooting, if nothing else creates a better proficiency.
Muscle memory, movement, tactics and technique, situational awareness, etc,... all count for something other than the previous example.
We have posted and discussed "range horrors", here at DRTV, and I'm certain there are competitive folks that create "horrors" as well.
I also know they are the exception, and usually these horrors are corrected...... I also admire Col. Jeff Cooper.
"I would add another reason - practice. Anyone who has ever been deeply involved in warfare knows that the only way to learn to fight is to fight. This may not be a popular view with the grass eaters, but I defy them to disprove it."
Jeff Cooper