I've heard the phrase "all day" used when commanding a kitchen brigade. It's generally used in a phrase like "I need 3 filets .. all day". What does this expression mean in this context? And what is its origin, if known?
According to this site on restaurant phrases, all-day means:
that you are counting particular items on the ticket rail, as in "Yes, chef, there are six chicken saltimbocca all-day, three beef tenderloin all-day," and so on. This counting method is a safeguard against forgetting to fire the requisitioned amount of food, especially when the dining room is full and the rail is lined with greasy slips of white paper. Things do get hectic during the dinner rush, and a basic "all-day" count can save your ass when you are plating food.
There is no etymology I could find on where this phrase comes from, but in non-restaurant English all day has been around since c.1000.
I couldn't find where the phrase actually comes from, but it seems to be fairly recent slang. The earliest example I found is in this definition from a May 18, 2000 article called In Every Great Kitchen, A Great Expediter by Anne Willian (Los Angeles Times Syndicate):
From time to time, a good expediter will cross-check with the cooks, calling, "I got for you five mahi-mahi, three cod and three salmon, all day." "All day" means the total orders of each item now in the fish cook's hands. It is a reminder and, at the same time, a check on ingredients that may be running short.