As far as I know, ANA is one of the few operators to use widebody planes for short haul routes (a Japanese phenomenon). The wear and tear of an airplane engine is mainly determined by the number of takeoffs and landings and not necessarily by the flight hours, hence normally narrowbody engines come in for overhaul after ~5 years, whereas widebody engines are being overhauled every ~7 years.

There are also other factors such as the cleanliness of the air (a lot of sand in the air is a problem) and outside temperature (hot and high takeoffs) contributing to how quickly the engine (or more specificially, the turbine) depreciates.

My impression is that ANA's problem is quite airline/user specific since widebody planes are not usually used that way.