I know this topic comes up a lot. All I have to go by is my experience. I work as a security guard for 15 years, mostly at night.
I carried good lights but the only time ever actually needed my flashlight was for utility tasks.
I worked at a FedEx shipping hub for 3 years. The first year FedEx was there so there were trucks parked all along the fence. I used my light to look underneath the trucks.
The only thing close to a "Tactical" application for a flashlight that I ever had was approaching unfamiliar vehicles on client property after dark. That, and pissing off the Hookers turning car tricks outside the fence.
Even the very few times that I had to clear a building I never went into one where there wasn't sufficient ambient light for me to see what I was doing.
I think I've discussed this here before but the only person that I'm aware of who has actually compiled a detailed list of Citizen involved shootings was Tom Givens. The most important statistic that I want to pull out of this is it of his 66 shootings the overwhelming majority occurred during the hours of Darkness. He defined "Darkness" as 6:00 p.m. to 6:00 a.m.
The Following is quoted from a post that Tom Givens made on Glocktalk several years ago.
"Parking lots in this country are not dark, with rare exceptions. Commercial locations, especially, tend to be very well lighted. I have seen my sights better on a convenience store parking lot at 3:00am than on an overcast day at 3:00pm."
during the entire 15 years that I was working as a security guard I cannot point to a single instance where I would have been better off with a Weapon Mounted light or that I felt like I needed a handheld light for a "tactical" application.
the only exception to that is one night I was walking around the perimeter of an electrical substation. It was it's the only one in town that I am aware of that is surrounded by a concrete wall. It's also the only one in town that I'm aware of that the perimeter lights weren't enough to light up the patrol path.
So anyway, the way I did my rounds at that particular substation was I'd walk so far down the wall, turn on my flashlight and scan around me, turn it off and move. One time when I did that I got to my stopping place and I turned on my light and there was a drunk walking through the field next to the substation and I lit him up.
He wasn't on company property he was none of my concern all he was doing was stumbling through that field trying to get home. I apologize and I think he cussed me out but that was the end of it.
So that incident taught me the value of a good light but I still can't think of another time that I actually needed one