It is true that using 2 stairs is quicker but ba, Lufthansa, virgin and city flyer turn arounds are not quick even add klm and regional to that mix, plus the numerous charter airlines with aircraft like 757200 landing here so there would be more use than just stand 7. Plus plenty of times u have 2 shuttles, a flyer, klm, lufty and regional plus now virgin all parked at the main terminal, only one low cost airline uses Abz which is easyjet