The restore nobody tries until it is too late

A copy you have never checked is a promise, and promises fail at inconvenient moments.

Backing things up feels like the finish line. It is not. The purpose of a copy is not that it exists, it is that you can get your things back out of it when you need them, in a form you can actually use, on a day when you are already upset. Almost nobody tests this. The copy is made, the drive is put in a drawer, and everyone assumes the other end of the arrangement will work. Sometimes it does not, and the discovery happens precisely when there is no fallback.

The failures are usually mundane rather than exotic. Something was never included because it lived somewhere the copy did not reach. The copy stopped running months ago and nobody noticed, because nothing announces itself when it quietly ceases. Or everything is genuinely there, but it needs something to open it that no longer exists on the new machine. None of that shows up while things are fine, and all of it shows up at once when things are not.

So the habit worth building is embarrassingly simple: occasionally go and look. Find a handful of things you would be sad to lose, and confirm you can retrieve and open them from the copy rather than from the machine. If they open, you have proof rather than faith. If they do not, you have found out at a moment when the original is still sitting safely on your desk, which is the best possible time to find out.