Apart from the purely economic considerations related to aircraft utilizations, the airlines of course have to make sure that their longhaul flights are scheduled opportunely for maximum connectivity at the home base. The greater the number of banks in the hub, the easier the scheduling task.
For an airline like Emirates, with mainline longhaul operations and a restricted number of aircraft movements at the home base, the number of arrival and departure banks is inevitably limited. As a result, Emirates is forced to schedule most South East Asian and Australia/New Zealand traffic to arrive at the DXB
-hub early in the morning, in time to catch the outbound European bank between 7 and 9 am. This is turn results in some undesirable scheduling and longer than necessary ground times at outstations.
Airlines that are larger and coordinate a greater number of aircraft movements are able to design a hub operation with a greater number of connecting banks. If their operation grows large enough, even a depeaked hub is a possibility. Such operational structures allow for increased scheduling flexibility and, as a result, more optimal utilization rates.
An airline like Lufthansa does not need to make sure all of its overnight longhaul traffic arrives at the FRA
hub in the 5.30-6.30am window, in time to catch the first outbound wave at 7.30am, because Lufthansa's operation is so large that the airline can accommodate another departure bank just a bit later from 9.30am onwards. This allows the airline increased flexibility in scheduling, and reduced ground time overseas.