Is there a matrix? Is there a decision tree? Is there a threat assessment?
That's kind of an interesting way to put it.
I like variety, but honestly my gun selection was very much common placed guns and cartridges, until I started reloading my own. Once I did that my willingness to start shooting different cartridges expanded. Having that variety provides me three benefits as I see it.
1. It gives me variety in the event of any particular cartridge being hard to find due to panics of various types, be they political, environmental, or virus related. (Seriously I can't believe the panic going on right now.
2. It took me down a road of expanding a hobby into something I do really enjoy. When I'm loading, I'm not really worrying about anything but what I'm doing, because you need to focus.
3. It allows me to just have a better optimization of gun and cartridge choice for a given situation. Evidence points to 9mm, 40 S&W, and 45 acp all performing very similarly. But other juiced up cartridges offer enhanced performance.
So the answer in my mind on that, is yes, where ever I'm going the quick decision tree I go through in my mind is:
1: What is the potential threat and the associated difficulty of stopping that threat. (Cartridge)
2: How many of that threat am I likely to encounter. (Capacity)
3. Will I be around people? (Concealability)
Typically those decisions get blurred into one quick analysis. Then I grab a gun and go. The potential chance of a bad encounter doesn't enter into it for me. I rather assume it will occur, and then I bring enough gun to give me an advantage. Whether or not I am bringing enough gun is up for debate.
And if you do a threat assessment and you decide the threat is such that you need to up armor why are you going there?
This is not a simple answer for many people because mental attitude and in some ways philosophy come into play, but the question gets at the heart of one of the principals of carrying at all. I've heard many times, if you know you are walking into trouble, bringing a gun isn't the answer. Avoiding the situation is the answer.
However, at times legal requirements take some city folk in to places they'd rather not go. I can see in those situations a person wanting more capacity than not.
I have an inherent draw to the natural world, I always have. I need to visit the forest on a regular basis, or I get very depressed. I chose a career that takes me to the woods regularly and causes me to live in a forested location. While most days you go to the woods or any natural environment, and nothing particularly exciting happens, other days you go and you are encountering animals, or weird people. Sometimes you see fantastic scenery, and other days you are getting beat up by hail. I remember being in dangerous lightening storms, on foot, and being really scared. I remember listening to thunder all afternoon and thinking "no biggie". Then a funnel cloud went sailing by and it was time to get out of there. I've been bit and chased by animals, had a gun pulled on me, and watched dead trees crumble and fall where I had been standing not 5 minutes prior.
Call me a low level adrenaline junkie, but that bit of risk and excitement makes me feel alive. I regret none of those experiences. I look at that early part of my career and realize those were the good years. When you really enjoy the natural world like that, folks tend to want to experience the variety out there and are willing to go where large and sometimes dangerous animals live for recreation. I can't control the environmental factors of course, other than watching the forecast. Defending against a potential large animal encounter is the one part I can control, though a gun is the final means to do so. Give them space.
So for someone like me, the need to carry a more powerful gun at times is just a part of life as I'm not willing to stop doing what I do for fun as it's needed for my mental health. A 9mm will not cover all the scenarios I choose to put myself in. That attitude may get me killed some day, but I widow no one. So I buy different guns, and I hike.