With the intro of long range flights reaching some 15 hours plus with multi crews, one would think that gives enough rest to the non flying crew members having a bunk to sleep.
I think 12 hours (2 crew) in the seat is a longtime. Trouble is that can be split into 2 x 5.45 sectors. The 30min turnaround means 1 of you is in the seat for 20 mins of that, and you were in the seat 20mins before departure. So how is the 'rest' accomplished? The new concept of 'controlled cockpit rest'. Joke. 12 hours with an aluminium tube strapped to your backside and no room to stretch your leg, all starting at 05.30 on day 5. Good game.