In 2011/2012, I did security work at a low end hotel property in a urban area(hookers, gang members, thugs/fugitives, etc). I had
several incidents where only
one police officer showed up then made a
arrest. My city's PD claims they are "under-staffed" & plan to hire several new officers.
Many sheriff's deputies, police officers & state troopers/highway patrol do arrests or detain subjects
alone. When possible they request other officers but that's not always a choice.
I also don't get the "carry a concealed gun, but never draw it" mindset.
Yes, you should be prudent & use caution in critical incidents, but you shouldn't be risk adverse either.