Used to work 12 hours 4 on 4 off a few years ago. Best shift pattern going. And fortunatly we all decided that we would rather do 4 nights in a row rather than doing nights on all shift patterns.
So did DDDD XXXX NNNN XXXX much better if you don't mind the hit of 4 nights, and better for your body clock as you only hit nights every 12 or so days rather than every 7 or so!
I do miss working half the year, now I am back to reality on Monday to Friday!