To haul wagons past the intended receiving station and then take them back again would be very unlikely, especially as has already been mentioned, on longer lines such as the WH and C&O. In my own experience at A&T the northbound would arrive, couple off the engine, go round about and catch the tail end of the rake (which if marshalled correctly, should be for A&T), move back to the Glen Douglas single line then be handsignalled through the facing road into the up loop, then into the head shunt before shunting back into the yard - this may have had to be done in more than one 'bite' off the up loop depending on how many wagons were to be detached. When finished the engine went via the up loop to the Ardlui end then shoved back onto the train and away north. If a brakevan were involved it would of course had to be coupled up to the back of the train again first. I've also seen a simpler method where the northbound ARRIVED in the UP loop via the facing road then carried out shunting from there.