Replaced a 5+ year old Panasonic that had heavy use daily.  On some weekends with family over at our house, this is used to cook several 1 pound bacon packages,  which repeatedly runs the unit 10 minutes at a time.  Definitely the stress from longer operating times are harder on the microwave generating "magnetron tube" and electronics.  Most other namebrand household duty microwaves lasted us only a year or so.