Premature Rear brake replacement

My neighbor has a 2005 and constantly has to replace the rear pads after a couple of hundred miles.
He has replaced the calipers and the guides are lubed. We flushed the system and still he has the same problem

Any ideas? I'm thinking maybe a proportional valve?

BOTH SIDES do this?

If you jack up the rear end, and apply brake, the wheels should not move......release brake, do they move freely?

Good advice from Tech11, this is step one, if the wheels drag, loosen the bleeder, if they free up, look for a flex hose that is common to both wheels, it may be collapsing internally, acting as a check valve.

Yes both sides do this. I just talked to a buddy of mine and suggest that it could be the flex hoses collapsing inside. I will check that and make sure that the wheels turn freely if the weather is decent tomorrow. Thanks for the help and advice.