Originally Posted by
flyallnite
Wrong.
The FOM defines 'should' as follows-
"The word 'should' is used to indicate that compliance is expected. Deviations are permitted only where an operational requirement exists."
The word 'may' is used when compliance is not mandatory.
Physiological needs are an operational requirement. I'll be getting coffee, using the bathroom, or getting a cat nap. All physiological needs which make deviations permissible.