Do you ever swear by a tool that objectively doesn't work?

I've tuned the same rank of pipes for fifteen years with a tuning hammer I know is off by half a degree — every young technician who touches it hands it back to me like it's cursed. But the organ sounds right when I'm done, so I keep carrying the damn thing. Just wondering if anyone else has a piece of gear or a habit they'd never defend but can't stop using.