As many of us on here have said, the gun you have with you will always beat the one you leave at home because it's to heavy, bulky, or just a PITA to carry.
As to those of us that carry low capacity firearms, more often than not, my 686 or GP100 is a primary for me in colder weather, with a 5 or 6 shot snubbie (Lately the Charter Arms Off Duty I picked up a few months back), with reloads for both is what leaves the house with me. Quick runs, either the PF9, LC9, or the SP101, Off Duty, or even the LCP or Hellcat in the pocket, depending on where I'm going.
If it's for the towing company, I always have a BUG, and a full size such as the Hardballer and the EMP, or the LC9 as a BUG for the 92FS. Or the G19 as a primary.
And I train and practice with each of them, as well as having learned with BA and single shot rifles and shotguns, so I make my shots count from the first, to the last.
And yes, I do know that most SD encounters are les than 3 round encounters, but, there are times when, especailly running security for a repo, where you don't know if one person will come out to stop you from "stealing" their car, or 10, most of them armed, instead. And most of those jobs are NOT on the good side of town, and few of which have been at drug houses in the past.
I also live on the "Wrong Side" of the tracks, in the middle of the "East Side Shooting Range." (From 18th to 24th, and Ash to East. This is where most of the shots fired calls come from in Erie.)
And I have yet to feel under armed with a 1911, revolver, or other non polimer pistol, with a "Low" capacity. Or even the Bersa Thunder, or LCP for that matter.