Clearly GNE allow too much running time if buses are always sitting in St Marys Place, or drivers are running early.
GNE seem to lose out in the Haymarket as very rarely is there not a bus on the Arriva 306/308 stand but often the GNE 309/10/11 stand is empty, GNE drivers waiting in St Marys Place until they see the bus in front coming out and then pull round.