Maybe this is a fall out of the pax compensation rules. Companys using any legal airframe they can get.
Most of the subs I have done have been for max three days when an aircraft is AOG.
Most of the time its been "get there ASAP your going......."
Even had one where the CP turned up at the aircraft door while it was getting put to bed after he had gone tech on the stand next door. 30 mins later we were on our way with thier Hostie down the back as company rep. And she was more worried about the bar than what we were doing in the front.