Where did the key go?

I turned something that just happened into a blog post as-is.
While getting ready to go out, I could not find my keys.

The setup was roughly this.
・I keep small items — keys, wallet, mask, and so on — in the shoe cupboard.
・For keys, there are two including the spare, and both go in the shoe cupboard.

And when I went to take the keys out of the shoe cupboard, what happened was: "there is only one key."

My thinking process at that moment went like this.
"If it is not in the shoe cupboard, it must be in the living room. Because this has happened many times before."
But it was not there. Then:
"It is not there. Why not? Do I already have it?"
Check pockets.
"Not in my pockets either. Did I leave it in the bathroom? No, there is no reason I would put it in the bathroom..."
Check the bathroom.
"Still not there. Let me check the shoe cupboard again."

In the end, the spare key was hidden toward the back of the shoe cupboard. Another small item had been blocking my line of sight.
In other words, "there had been two keys in the shoe cupboard from the start."

It is an ordinary story, but while heading out I was thinking:
"Why did I not carefully check the shoe cupboard first?"
The answer is clear if you trace the thinking above.

To repeat:
"If it is not in the shoe cupboard, it must be in the living room. Because this has happened many times before."

In the end, as an intuitive judgment, I acted on experience.
Ah, I messed up — I reflected.

While thinking, I remembered Daniel Kahneman's Thinking, Fast and Slow — System 1 and System 2.
(Simply put: in snap judgments people pull in experience-based intuition; when they have room, they tend toward logical thinking.)

And then, to top it off, this:
"Not in my pockets either. Did I leave it in the bathroom? No, there is no reason I would put it in the bathroom..."

I compared the rarely plausible "probability it is in the bathroom" with the "probability I overlooked it in the shoe cupboard" — and chose the former.

If you think carefully, the latter is probably higher, and that should have been the priority action.
It was a trivial everyday episode, a mistake with no real damage.
The cost of acting and the cost of the mistake were both near zero, so if you have time to deliberate you should just move — but still...

I do not need to reflect deeply — but it was an embarrassing episode that showed I had been assuming I think reasonably well.