I've been always wondering why airline rules stipulating "no alcohol for a minimum of eight hours before reporting for duty"? It all depends what you drinking (two bottles of wisky or a glass of wine), who you are (45 kg female or 110 kg male), what's your experience (if you drink very regularly in large qtys it causes much less effect on you), and finally it depends of individual body's metabolism.
Our airline stipulating min 48 (fourty eight!) hours before the flight and that's our CAA request
I believe it would be fair to measure/regulate/prescribe max amount of promilles only rather than stupid time period limits...