There was a bloke that went throught ATC SKOOL about the same time as me who got stuck in the simulator for months during his field training with nothing to do but do unsupervised sim runs on the sector he was to be trained on when the sim wasn't doing anything else. In no short time he had memorised all the available exercises & reinforced any and all bad habits he had to a formidable degree, leading to a jaw-dropping experience for his trainer when the real training program commenced.
"Womble242, request FL370."
"Womble242, not available due crossing traffic."
(trainer) "What traffic?"
"Bungair11, out of Blergle. He doesn't depart for 10 minutes so we don't have a strip yet..."