I'm too old for school unfortunately, but I know that my insurers would pay out if my watch was nicked from the locker at the gym.
Nothing to do with luck.
Yes, nearly all the time, so a much reduced probability. Unlike say a smartphone or an iPod, which I'm sure loads of kids take to...
Don't the insurers have to have a bit of trust and accept the balance of probability that, if the lad had one watch, then there'd be a good chance that he'd wear it to school? If that wasn't the case, the extra premiums I pay to itemise my watch on my home contents insurance would be worthless...