Can't agree to that one. Yes, a pint of ordinary strength beer metabolises in about three hours, so four pints. However, I understand that the modern machine will pick up the fact that you had a liqueur chocolate last week!
In my last few years of working, I only drank on the first night of a two-day break, giving over 36 hours abstinence. Boring, but safe. Since retirement I've become teetotal, and enjoy some of the better alcohol-free beers now being produced.
I guess my company was very enlightened. We had a pilot with a bad alcohol problem, and the company did everything it could to help him dry out. Sadly it didn't work, and he had to resign, but they tried.