Delta had 13.3 weekend crews(fri/sat/sun) in the hangar (and 5 days/8 hours weekday) and they took them and replaced them with 3 days 12 hours and then make up days(mondays of 12 hours) and the guys here went nuts. Funny to see so many people against them at AA yet so many for them at Delta. Midnight weekend crew on 13s was greats. That make up day sucks.
anyways, the reason for pulling them was a "study" that said they were less productive then 8s/10s/12.