The statement I made was based on hundreds of repaired chain failures in V8s. The only other motor we have seen more than "ONE" failure are the 615/616/617 motors where we have seen maybe 20-30 over 25 years.
I have seen a couple 16v 190's fail and sold parts to someone doing a 103 motor that failed, but it is NOT a common occurance. We are currently doing no preventative measures on 102/103 motors. That might be reconsidered as the fleet gets over 200k. We advise upper chain rails (three only) on all the V8's at 75k intervals and chains at 150k.
All the motors that have no problems, use ratcheting chain tentioners. The problem with the rails is that they become brittle over time and there is no way to prevent the wimpy hydraulic tentioner (on V8s - no ratchet) from occationally loosing oil pressure after sitting (which rattles the chain hitting these rails which otherwise never contact the chain).