Schedules are a key factor in an airline's profits.
They influence many aspects of the company economy like the commercial impact, cost efficiencies, punctuality and indirectly the company's strategic position.
At the same time, schedules also form a threshold for change. So many aspects are tied together via the schedules that one adjustment can easlily lead to a chain reaction of other changes.
That makes schedule optimization one of the most complex topics in airline management.
More about the influence of schedules on company profits here...
Here are some posts with more backgrounds on interesting scheduling subjects:
Wrong indicators grounding airlines
On how airlines in trouble make their situation worse with adverse production cuts.
(c) Schedule Consult Bvba, Belgium