Some airlines mandate the crews to fly at max efficiency, which is a slower cruise mach. Exceptions being strong head wind component, delays that require higher speed etc. But I think the general consensus is that a lower cruise WILL save fuel. Other fuel savings measures are would be an idle decent so with again a lower speed, thus the engines are at idle thrust for as long as possible. Usually these come into force when jet fuel prices begin to climb. It could amount to a :30 minute longer flight on a transcontinental, but on the short hops doesn't effect the times too much. They will factor that into the new sked if these policies will be SOP.