The cutting ends off ham and defrosting chickens reminds me of the story Chromium, in Primo Levi's The Periodic Table, where he relates exactly the same blind following of a formula in various paint/varnish factories during and after WWII. In one anecdote he tells how a prescription book called for two slices of onion to be introduced into linseed oil as it was boiling, which he thought odd to say the least. It turned out that before thermometers had come into use the temperature of the oil had to be assessed by other means, one of which was to immerse a slice of onion into the oil and if it fried, the boiling was finished. "Evidently, with the passing of the years, what had been a crude measuring operation had lost its significance and was transformed into a mysterious and magical practice."!