With regards to the last comment, the use of Hi-Fly is to do with the engine issues with the Dreamliner - the same issues Virgin (and many other airlines) have had which caused them to bring A340’s out of retirement to cover!
Unfortunately Norwegian do not have that luxury and therefore do whatever else they can to ensure they aren’t cancelling your flight!
Regardless of who you fly with, tech issues happen to everyone. Some may be better prepared but they are also a lot more experienced with Long Haul Ops!