Hours are only "part" of the equation......"CYCLES", will be a "huge" part of what an airframe may survive????
Whether a 737 has 40,000 hours airtime, pales by comparison to 160,000 cycles, for a takeoff and landing !
We have "Cranes" that have logged over 50,000 hours......but the cycles of a "lift and landing" are almost beyond a mathematical equation (ie: hard landing/ overtorque) ????
My point is.......the company operating an aircraft should "know", the weaknesses of "said aircraft"......and have the maintenance department carry out the inspections and work required, to keep the aircraft "airworthy" (SAFE) !!!!!
At the end of any work day......the only thing that is important, is the "flight crew go home safe and sound" !!