An experience I have all too frequently is buying something I already own. And using it before I discover that I had it already. And I spend far too many hours searching for things I know I have, only to have them turn up months later...
The other day I was looking for something (I forget what) and I came upon a heavy duty two-prong plug. A few ago I went to several hardware stores looking for a heavy-duty two-prong (no ground) plug to replace a broken plug on a vacuum cleaner. I ended up buying a three-prong plug and sticking an adapter on it. On Saturday I was looking through my shop for something else (I forget what) and I found a never-used heavy-duty two-prong plug.
A few weeks ago I used a self-centering drill bit (a Vix bit) that I'd had for years in a clear plastic case. When I was done, I couldn't find the case--even though I had had it just an hour before. A few days later I found the case and now I can't find the bit. I've turned my shop over looking for it. Still no bit. I had to buy a new one.
A few months before that I'd been using a porter-cable orbital sander hooked up to a vacuum cleaner for dust collection. When I went to put the built-in dust collector back on the sander, I couldn't find it. A few weeks later I found the dust collector, and now I can't find the sander. This is the first time I've mislaid something that big.
It's not a tool, but I bought a lawn sprinker to replace one that broke. Two days later I found the even better lawn sprinkler I'd bought last year on sale, to be prepared for when one broke....
It goes on and on...
I guess I should clean up my shop.