Havin Fun-
Sooner or later the major(s) will happen, in spite of everything we try to do preventively. My majors have never been from something I keep maintained like tires or fluids (except for the time I ran out of gas in the middle of Hwy 101 - I thought I still had 10 gals.:o), they've all been caused by something unforseen and seemingly built to fail.
Like a bad in-line starter relay 6 mechanics in 6 shops didn't know existed and was artfully hidden from view by General Motors, then replaced by a hardy solenoid on the production line in a timely fashion 2 weeks after my chassis was built. Burned up 4 starters and got me towed across Montana and Wyoming several times before I investigated and found the 1984 Chev shop bulletin and fixed it myself :p.
Or like the bundle of wires that Fleetwood Riverside had routed through a torched and jagged frame hole and over a muffler; lucky my coach didn't burn up on that one - my at-the-ready smoke smeller was on the job :E.
And the countless near-misses; disasters prevented by either routine inspections or inadvertant discovery. They point up the need for constant vigilance, esp. on older rigs that have worn or corroded from years of service. I regularly crawl under (and over) my Pace Arrow looking for potential problems, and inevitably end up refastening or resecuring nuts, bolts or wires, sometimes painting or coating or retapeing or replacing old parts. But you can never catch the one that Murphy's Law leaves for you, so when it comes to old Murph I walk softly and carry a big wrench :W.