I had a similar experience in my first job. I was a student engineer at a well known medium-sized electronics company.
One job I had involved making a change to a PCB. It needed a couple of pins lifting, and a trace needed to be cut.
I wasn't allowed to actually make the track cut, though. That was the job of one particular operator in the manufacturing dept. A student engineer wasn't allowed to do this, because modifying PCBs was
her job.
So, I handed over the board, pointed out the trace that needed cutting, and she set about it with a scalpel.
A minute later she handed the board back to me, and I checked it. The trace was exposed, but hadn't been cut all the way through, so I handed the board back.
She squinted at the board, scratched at it for a while longer, and handed it back to me. The trace still wasn't cut all the way through. (This wasn't a big, fat power track or anything - just an ordinary logic signal, probably 7 or 8 thou).
After the third time, the trace was still intact, but there was a deep gouge next to it, right down to the ground plane. Then it dawned on me.
She didn't know what was the track, and what was the gap between tracks. She'd been scratching furiously at the space between the track I wanted breaking, and the one adjacent to it. Any actual damage to the track itself had been accidental.
I died a little inside that day.