About six to eight times out of ten, when I go looking for a 1/4" or 5/16" nut driver, I can not find one. So, I go buy more when I am at the tool place. I now have them on my nightstand, in my truck ashtray, and various places around the property, except in the little tupperware bin I keep my bits in.
It's like those plastic grocery bags. You know, the free ones that you have about a seven year supply of under your sink. And still put every last one you get in with them. Hell, the plastic is decomposing on some of them, it's so old.
How many unfindable nut drivers do you have. Insert your favorite thingus in the "nut drivers" location.
Steve