It's really pretty amazing, how many cameras and/or other photo gear items fail for unknown reasons during weddings, in particular.
I've only shot a handful of weddings personally (I try to avoid them)... and have had gear failure or breakage at three different weddings.
One time it was a locked up shutter in a film camera that worked fine before and after the wedding. It was sent in for a CLA a short time later and still works fine today, but I'm keeping it away from weddings.
Another time an assistant dropped some gear and put a camera temporarily out of commission (broken battery holder... I got several spares after that).
Third time I made it through the ceremony unscathed, but at the reception a drunk guest stepped on gear I thought I'd stashed in a safe place (destryoing a flash).
Meanwhile, I've shot all kinds of fast and furious sporting events, wild and wooly wildlife, remote travel locations, backpacked and camped with gear, and used it under very harsh conditions, sent it to a destination through UPS/Fedex, carried it onto airplanes... all with reasonable care of course... but very rarely had any problems and almost no failures.. ever (knock on wood!).
Call me superstitious.. But I really hate taking my gear to weddings! I always feel like I'm putting it at risk...
If there's any place that a 1D series camera... built like a tank... will fail after only slightly more than 10% of the predicted shutter life, it's at a wedding!