400
I've worked it at the same place as you, personally I found the 6 set really hard going, days worse than nights infact, hated getting up at 5ish to be in for 6, with the nights your body settled into a better routine as you progressed through the shift, but it's not fair on your families, especially at weekends.
The plus side is 2 weekends off per month and the 6 off is great. Bond Air services currently do 6/4/4/6 but with out nights, great shift pattern
