We have a similar technique, I put my stuff in the same place all the time. But only because I was sick of misplacing them for many years.
I think there are a lot of people that don't have tendencies towards systems/self rules to solve issues like this, so they casually smash through life care free and forget where they put their keys "this time". (based on many people I know)
It isn't a system I developed to remember though, it is just... I put them somewhere sensible where they won't fall behind something or scratch anything etc.
My keys are often in different places, it is just that the list of "sensible" places isn't very large so if I have forgotten checking them all takes practically no time
EDIT: I should say not a system I developed consciously, I do have ADD so my habit of putting things in sensible places generally might be an adaption to that, though if so it happened before I even had keys to lose
We may be mincing words, but when I say "system" I mean "I decided to try and only place my keys in reasonable places, always... and these 4 are the most reasonable."
Where other people may have made no considerations at all where they put stuff.
I feel like "System" is a bit of an extreme term. "Sensible" also means natural. Like, either they go on the kitchen counter, the dining table, or my desk, or occasionally the arms of the couch usually because those are the places that have space to put things like phone/keys/etc when I empty my pockets.
The only considerations are: Is the place convenient (read nearby when I'm likely to be putting things down)? Are they a flat and stable surface?
That's it. I feel like if people don't make those sorts of considerations surely they are just dropping shit on the floor
I think there are a lot of people that don't have tendencies towards systems/self rules to solve issues like this, so they casually smash through life care free and forget where they put their keys "this time". (based on many people I know)