When I was wee tech lad, and had about 2 months of Xenix use/self training/customer tech calls, my boss decided it was time to test me. He was a Unix admin, classic nerd, with deep AT&T and Berkeley connections.
He went through and fucked up the system. He changed permissions, contents of driver files, removed critical files, renamed them, it was ALL OVER THE PLACE.
And then he said: Fix it.