What happens most commonly is that the situation depicted in that thread first comes to light when a surveyor is hired to survey the land ON THE SOUTH SIDE or other adjoining sides of the tract depicted. No one seemed to offer any comments on what happens then.
The surveyor pulls the deed that says: All of the.......except (the tract depicted). He finds the aliquot corners and promptly goes about locating said tract. Oh, oh. His perfect survey discovers the back corners are WRONG! Time to start setting pincushions. RIGHT? He sure doesn't want the cranky old hag down at the title office to give him agony over a new description that differs from record.
The new description should match the record. The original conveying deed hasn't changed, only your measurements might differ.