It is indeed around 10.5 hours utilisation a day, day in day out, which is in itself pretty impressive for a 737. There are a fair few rotations to the canaries in there. German airlines were early and enthusiastic implementers of assumed temperature take offs and given the length of a lot of the runways used (FRA/MUC/CGN etc.) the benefits are obvious. I have on occasion been asked by the tower if we had had an engine failure when using derate 2 and max assumed!