I have worked 2 types of shift:
4-cycle 12 hour shifts, 33.3% shift allowance, 2 days eg Monday/Tuesday followed by 2 nights Wednesday/Thursday. We then have untill the following Tuesday off when the shift starts all over again for the next 35 years or so. This works out at 48 hours in 8 days which averages out as a 42 hour week. The 40th hour is banked as holidays. The 41st and 42nd hours are paid at double time.
5 cycle 12 hour shift. 33.3% shift allowance. This incorporated all holidays, bank holidays etc into shift structure. 12 hour shifts days and nights as follows: 2 days,2 off, 2 nights, 4 off. This adds up to 48 hours in 10 days or a 34ish hours in 7. Holidays make up the remaining hours. During the summers we worked 8 weeks of 4 cycle to allow each shift to have 2 weeks holidays. All other holidays involved shift swaps.
Found both shifts very good