For some older aircraft generic POH's are all there is.
OK, let's be more precise. For my TB20, new in 2002, the POH was entirely generic except for the W&B insert.
Was it any good?
No. Because while containing basic procedures like which knob to pull to operate the emergency gear release, it contained very little on avionics. It was basically a VFR and night-VFR handbook.
To make up a usable POH for say another pilot I had to photocopy this one and then insert stuff on the equipment actually fitted. This, even after removing crap like lists of amendments of amendments of amendments, doubled the size of it.