I've only ever seen a stick tang knife fail on two occasions:
Once when it's been used as a throwing knife by a stupid person who thought he knew better than I did when I told him that it would damage his knife
The other time was because the user was battoning through something hard and his technique wasn't the best. Should've used an axe.
A couple of years ago I spent a month going over my heat treating and just out of curiosity I also tested full tangs versus stick tangs. One of the destruction tests was to clamp the blade in a vice and using a 2 foot extension, to bend the blade until it set or broke. I started at the tip of the blade and had the scafold pole half way up the handle, gradually I worked up the length of the blade. Both types of tang gave out at about 1" from the handle. They both bent about 1" into the handle (stick tang broke the wood out, fulltang popped the scales off), it took about the same amount of force and the same amount of deflexion to do it.
Whenever people try and tell me that only a fulltang is strong enough I point out that virtually every heavy chopping or salshing tool around the world and throughout history has been a stick tang: billhooks, swords, parang, kukri (and that is a 12" baade with a 2" tang!!!)