Bikeboy,
Just some history for you. In Oz centres in the ol' days (green screen, shrimp boats and paper strips) there were no set hours at the console. You could be tethered to it for up to 8 hours (if your bladder was good enough).
Since we're now in TAAATS, a fully screen based environment. No paper strips, just keyboard and mouse, and your four screens per console, a decree was made on workplace health and safety grounds that in a screen based environment, a controller must have at least 20mins. break every two hours.
Doggos (that's what we call a night shift), doesn't count apparently, and you're stuck there for however long.