Airliners and business jets are built with a certain number of cycles in mind. A cycle is usually defined as a pressurization and depressurization of the cabin. There is no doubt that pumping up the cabin puts more stress on an airframe than does unpressurized flying. It was the catastrophic failure of the cabin roof of an elderly Boeing 737 that alerted the airline maintenance community to this problem. The DC 3 has flown for more than 60 years, and many light aircraft soldier on after age 40.
Corrosion is a constant problem for aluminum aircraft.
If they have not been internally corrosion-proofed and are operated in a wet or salty environment, they will rot much faster than in a dry climate. Piper Arrow for nearly a decade after it had been a trainer on the Florida coast for a number of years. My friend's steady diet of liver and onions also may have contributed to a corrosive atmosphere inside the cabin that led to an earlier demise of the aircraft. At the last annual inspection the maintenance technician could no longer sign off the old bird without extensive and expensive repairs, so the Arrow became an organ donor with her serviceable parts going to more viable machines. She was deemed unairworthy before becoming unsafe.