proper manufacturer approved inspection and preventative maintenance programme
To get slightly technical, but not much, the aim of an Aircraft Maintenance Programme is to ensure that the aircraft is in precisely the condition described in its Type Certificate, every time it departs, apart from a few allowable defects (which must be fixed within a stated time).
What you really mean, I think, is that aircraft and their components rarely, if ever, simply break; materials and designs are too good for that.
So a delay due to a technical defect of any kind is almost certainly the consequence of something which is in the airline's control; and quite often that "something" is a consequence of management pressures, at least in airlines suffering from financial pressures.
Not all airlines, even in one State, operate to the same standards. Within the limits set by regulation there is still room for cutting corners if you are that way inclined, at least in maintenance, and a complaisant, lazy regulator will only realise what's happening when the consequent crash is investigated. And complaisant, lazy regulators exist in the most unexpected places, such as next-door to Beehives.