I'd agree with Airplays experience entirely there, the odd few now and then are manufacturing defects which end up in warranty claims, but classic things such as wiring looms chafing on pipes/ducts are a result of poor mx, whn the a/c was delivered there was adequate clearance between duct and loom, when the pipe was changed, the p-clip was undone, someone drops a stand off and loses it, doesnt replace it and the clearance gone, 50 cycles later and a load of vibration, you get an IFSD.
I give an example, new a/c off the production line 2 engines "zero hours in service", first flight, left engine has 1.9 CTA
(Switzerland)">BB vib, the right has 0.2, the bearings, pipes, labyrinth seals etc etc are all given a good shaking and wear begins too occur quicker, small seeps from seals = more engine oil uplifts, engine begins too run hotter and burns a little more oil. Fan trim balance carried out and Vib gone.
The left engine is coming off wing earlier than the right. But the same may happen too the left, it could all come down too a filler seal not seated correctly !!
its a 'how longs a piece of string' question, but I agree with maintenance being the variable.
p.s, cant get rid of the CTA
swiss thing so ignore !