Lord Lucan...
Im response to your question our duty limits are regulated
12hour per day maximum with 12 hours minimum between shifts.
Maximum weekly hours is 72hours. We are subject to random unannounced drugs and alcohol screening with the usual periodic medicals.
The company that i work for work to a 5 day 35hr week which is averaged out over an 8 week cycle. There are some operators which work to a 4 day 35hr week.
Hope this answers your question
T-star