Beancounters v Those on the Lamb (sic.)

Every January, London Zoo (and I assume other zoos) do something that seems a bit strange to me: they count their animals. Once a year, they have a Noah-style stock-take.
The lesson of this? If you're planning a Madagasgar-style break-out, do it in mid to late January, then the powers-that-be may not notice for almost an entire year.
I think I may try the same principle with weighing myself as a once-a-year, frighten-yourself-silly exercise.