What sort of "state" is it arriving in?
It's doubtful that the labels would be wrong every day unless the walk names are wrong in the system, that would be based on what's in Route Planner
if a letter goes through the first IMP or iLSM that it passes through upside down, it has to stay upside down through the rest of it's journey to the DO. If it's put the right way up, the CSS machine will look where it expects to find the orange barcodes and not find them so it'll reject the item.
The sequencing sort plans are no longer written by MC staff, there's some office somewhere (probably Sheffield) where they write all the sort plans for the whole country