Maybe it was a particularly smooth and benign 7 years during which I flew on the N. Sea, but I don't recall any markedly rough conditions as a rule . Windy; yes, turbulent sectors on some 'rigs'; yes, but not during normal flight. Conversely, I've had MGB low oil pressure captions come on in the cruise in other arenas.....
I would politely suggest the 'rough air' theory is a non-starter.