Yep, locally where I am there’s one postcode for all the houses on one side of the street (all the even numbered houses) and another for the opposite side (all

Yep, locally where I am there’s one postcode for all the houses on one side of the street (all the even numbered houses) and another for the opposite side (all the odd numbers.) Presumably it helps a lot with validating the address is correct, kinda like a checksum, and also probably helps with how deliveries are organised by the local office before the postie is sent out with them all.