The thing about these bombers, they arent your toyota carolas, they are bespoke pieces of 50 year old hardware, imagine the attrition they take flying thousands of km for every sortie. There is only so much mileage the engines can take before they need to be overhauled or replaced, same goes for all other systems.
Ipso facto a 10% reduction in numbers will not lead to a 10% reduction in sorties, the multiplier is much higher, as planes have to be over-utilised and probably the freshest operational ones were parked outside and hit