I moved to Columbus OH in 1991 from the eastern side of WV, so I was 250 miles away from any family or friends. My little Chevy truck that came from the repo auction had a couple holes in the floor the previous owners made for mud and water to drain as they must have mud raced it. I taped over a hole and taped my spare keys there, it was back under the seat where it couldn't be seen from inside and was hard to get to from the outside as you had to carefully reach between the frame and front drive shaft.
So that first winter I started the engine and got out to scrape the windshield and when I went to get back in the door was locked. I reached my pocket knife under to cut the tape and when I punched through I heard a ping as a key bounced around inside. I laid down in the ice and snow and took my arm out of the coat sleeve and squeezed up as far as I could inside and was able to grab a key with my now frozen and dirty arm. Unlocked the door and got in and drove back to my apartment. Then when I got into my apartment I noticed I had the spare ignition key and not the door key, this was back when there were two separate and they were different. I went back down to the parking lot and tried that spare ignition key and it would not open the door lock. I used the door lock key and opened it and got in and found the spare door key way over on the passenger side where it flew when I punched through the tape.
Somehow, when I needed it most, that ignition key unlocked the door that one time.
I always kept spares in my wallet after that.
Also I see a lot of people who keep their BOB's, one of the things I've done is either put my wallet and keys and phone in the front pocket of my BOB or a spare set of keys in it. If the house caught fire and I needed to evac out a window I'd grab my BOB on the way, probably tossing it at the window first to break the window then have keys to get in either vehicle and start it up and move away from the house and have access to the heater and/or spare clothes.