The spare key hidden badly mistakes being out of sight for being thoughtfully protected.

Hiding something and protecting it are not the same act, though they feel alike from the inside. A key under the mat is invisible only to people who are not looking, and the comfort it gives comes from your own habit of not thinking about it. Most of what passes for safety is really familiarity that has never been tested.

Pick one arrangement you have called secure and ask how it would look to someone actively searching. That might be a key, a password kept in a drawer, or a document nobody has checked in years. Change the one that would fail first.