The risk with relying with "hearing" the timing chain rattle before it breaks is that many people won't hear the sound or recognize it. When it rattles, it kind of sounds like something from the exhaust and can sound normal. Not everyone has ears tuned like that. Also the rattle often only occurs in the morning when you first start it up, at least it did in my case.

I think people really need to change those chains and tensioners proactively and not try to listen for a sound.