I've never drink while working if I have to use a piece of equipment.
A beer on site at the end of the day, looking over stuff or while fooling around with rakes and shovels in a bunker, OK
At Sagebrush, we met in the Office (those who've been there know what it is), had a couple of pints, food and disucssions of the job and be dead by 8pm, relaxed and ready to sleep. Great times.