[PeterisP]

That is a factor for the length of the shift, but not the total amount - where I live, when there are professions that for various reasons need 24 or 12 hour shifts running continuously, the standard way to do that is "1 on / 3 off" continuous schedule which comes out to an average 42 hour work week. I.e., either you work for a full 24 hour shift and then have three days off; or you have a 12 hour shift every other day, no matter what day of week it is.

It has some advantages and disadvantages compared to normal work schedule (essentially, less commute but many of weekends/holidays away from family), but you can definitely live with that.

However, having 12 hour shifts every day? Just hire two employees then, because you have enough work that requires two full employees.