Some maintenance costs may be cyclical like tyres and U/C. Also engines will tend to last longer if they can be treated gently. (I flew with a Captain who liked to hear his Merlins backfire. He left the Company for another reason.)
A Salty atmosphere may tend to corrode, this is more likely in the bits that are harder to get at. ( During the AirLift salt had to be flown to Berlin in flying-boats, which were designed for salt water.)
Some electrical bits do not like being switched ON. Where possible, leave them ON for the "working day". ( The earliest computers HAD to be left on to get any reliability - and it got hot in the summer, they said !)
Condition Monitoring may be possible, perhaps something like Oil Monitoring, to check the engines for their condition, perhaps giving better warning of impending problems.