From what I´ve seen on damaged A7750 pictures and read about them, no mater how carefully You wind a non-serviced A7750 it will grind and wear several gears. The fine metal dust goes between everything inside the movement clogging it up, producing additional tear and wear on all other parts and by consequence the power reserve gets less and less until the winding gear teeth don´t wind any more because they are totally worn down. All this starts after the first full wind already - and it may have been previously winded by the TD. Solution is a full service.
I don´t wind any A7750 at all, never. They start to run when I pick them up and easily have a PR of over 12 hours, 24+ if on the wrist longer.