Perhaps everything was indeed freely moving and relaxing for the piston and caliper assembly.
What is the possibility the the pads were new and installed on a rotor with a gouged inboard surface from earlier metal on metal mishaps? If the outboard rotor surface is pretty good, pad wear will be near a normal rate. But if the inboard rotor surface is over-rough, it will carve the pad down pretty quickly.
You would have to know the history of the situation to decide.