Talking about CP/M
Going back a very long time, when CP/M was dominant and 10MB hard disks were an expensive rarity, I was testing a format program I'd written in assembly language for a very non-standard carttridge hard disk drive. I'd just fixed a minor problem, put in a blank cartridge, ran my program for a short while until I was happy, then stopped it half way. I thought. So I took out the test disk, put back my work disk with all my source code, and then noticed my program carrying on formatting from where it had left off, clearing everything from the middle of my precious disk onwards. Didn't do that again...