I think it's unfair to expect people to stay teetotal just on the offchance they might get an unexpected trip.
You should be on the flypro, or on an official standby, or should be given a definite period that you are free for - eg 'you aren't on standby, the earliest you'll be airborne is 12 hrs from being called'. It's a career, not a job, but it isn't a calling.
Wartime it all goes to pot of course - but it's not fair to expect people to spend years sitting in flying kit next to the phone, being grabbed at no notice so they can go do a training sortie for practise just 'cos some airframe came 'S' unexpectedly.
(In wartime getting pi$$ed is part of the preflight, anyhow).
Harry Staish, early hours of yet another holiday ruined...I'd landed after another 8 or 9 hours of buoy loading
HS: - 'Are you coming or going?'
Me: - 'Wish I fecking knew, Sir'
(All that saved me was that I was in Int drinking coffee by the time he'd believed his ears. Mind you, promotion and myself were pretty much strangers over my career).