A_A, curiously the amount you suggest is feasible in the evening was not far removed from a normal lunchtime.
While Craig I think, though it could have been Sir Peter Hardup, more or less banned lunch time drinking, before that it was almost the norm for desk officers to be pie-eyed until late afternoon.
I recall one sqn ldr ops at a maritime base pre-FI who was invariably squiffy until tea time when he might start work. Or our dark blue brethren with their measured calorie controlled intake at lunchtime.