where I work at Stansted, we work 4 on 4 off, as you said, we take 1 1/2 days leave per day requested although our B/H are at 1 for 1
If however you work out hours worked over a year, you will find that a 12hr worker actually does more hrs than an 8hr worker, to the tune of 13days at 8hrs.
regards
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Not all those who wander are lost;