Our Class C MH is about 11 years old and I have had to perfrom some minor repairs/improvements here and there on it. The only major failure was the Ford E450's TorqShift transmission after around 61K miles - which may have been related to my driving habits.
However, whenever I repair anything on it I always try to repair it so that the same issue will never occur again. I other words, repair it better than what it was when new. Usually this requires using a "better design" when fixing something, as opposed to repairing it by merely restoring something back to exactly like it was. Sometimes, but rarely, is a "flat out better component" available for a fix so the issue never occurs again - only a better way to use a new stock or standard replacement component or use of an entirely different type of component.
Even with the failed Ford transmission I had the transmission shop install a heavy duty version of the transmission - so as to get a superior design or quality level over that of the original.
Using this approach to repairs should gradually (and hopefully) over time begin to diminish failures ... even though the RV is of course getting older.