My two hexagonal cases for concertinas have locks but only one had a key when it arrived at my place; the other now has a key that I found in a collection of antique keys that came my way because friends know I curate old stuff. Other types of (and more modern) cases have locks but I suspect the keys have been lost; they tended to have only about four variations anyway and were not worth keeping, let alone using. Keys that once were required but are now irrelevant I use as scrap metal.

Work has involved more keys than I can carry so I keep all except the ones to enter the building and my office in my office; but I wouldn't say I "own" them.

The rest are as minimal in number as I can organise and still operate the house and the car(s).

Cheers, Rowan