My 715/714 were delayed for an hour on Christmas Eve. Spoke with the crew on it and it seems calling sick on “less favourable” flight is not uncommon (I guess also taking into account the festive season).

715/714 are operated by the same crew so technically a >12 hours shift counting when you leave home and back home.

P.S. I should clarify when saying crew, I’m extending it also to the cockpit!