Rule is rules. When I did my military training, a lot of the older instructors were ex-WW2, and we were expected to "be in the bar until it closes, breakfast at 7, brief at 8, airborne at 9." Then it was an 8 hour rule, or generally 3 hours per pint (remembering that you are processing the early ones while still drinking the later ones). Then it became 12 hours. Once the random testing was introduced, I stopped drinking a minimum of 24 hours before duty, since the AME had told me traces sufficient to ground you can be detected up until then. It meant really only drinking on the first night of a two-day weekend, but that was the only way to stay clean. Thankfully I'm now retired and it doesn't affect me; the bummer is I'm on medication which prevents any alcohol being taken.
