I've had a problem with a few of them burning out but I do believe it's because of the atomizer placement in the cartos. In some of my carts, mainly blanks - the wire will be up against the side wall, causing the metal to heat up and litterally cook the carto. Burnt my lip on one of them, after a few hours of use the color of the cart started to fade in the area that the wire was touching so it was easy to spot which cartos were really acting up.2 duds in one pack last month.
Ordered premium cartos that should be here today. I hope they don't have the same issue as from what I read, the new ones do better with heat?
Though if you let your cartomizer get too hot, will it waste juice? Could it degrade the flavor also? Never really put much thought into it but I suppose it could make sense. It's just a shame though considering I like it hot for a better hit.