How many rounds minimum are borderline sufficient in your semi auto pistol?
I prefer not to go below 6 round magazine capacity for a pistol. (I didn't feel under-equipped when I carried a 6-shot service revolver, FWIW.)
That's a minimum, though. Several of my retirement CCW pistols (formally off-duty weapons) have 7-8 round mags, which I tend to prefer, all things considered. (I spent enough years carrying my 70's vintage Commander with 7-rd mags, after all.)
Then, there are my higher capacity pistols that have 9-10 round mags.
I even have a hi-cap pistol similar to an issued one I used to carry on-duty, which has a 12-rd mag.
All of that said, as a long time revolver owner & user (on & off-duty) I'm certainly comfortable carrying one or another of my 5-shot snubs.
I've carried a weapon with a badge & ID for over 30 years, and I spent a good portion of my career working in the capacity of a firearms instructor and armorer. I have a passing familiarity with firearms and the need to develop & maintain proficiency with them. I'm not unaware of the potential for unexpected dangerous circumstances to arise in the course of our otherwise normal lives.
I focus more on training, practice, awareness of the laws, experience, awareness and mindset than I do on how many rounds any particular handgun may carry before it has to be loaded again.
I once reflected on the fact that I began my LE career carrying a 6-shot revolver ... and then went through that whole hi-cap phase where we were carrying issued pistols with mag capacities 12, 14 & 15 rounds ... and I finished my career carrying an issued pistol with a 7-rd mag capacity. Full circle, so to speak.