My tensioner never made any noise whatsoever before it failed without warning.

I'll usually notice when something sounds different or out of the ordinary. I noticed the sound of a very slight exhaust leak, on start up which was coming from my driver's side Cat. Once the vehicle warmed up the noise was gone as the metal expanded enough for the leak to be essentially sealed. It turned out to be a hairline crack around the perimeter of the weld on the Cat. My point is I think I would have been able to figure out the tensioner was about to fail if it gave any warning. But then maybe not. Thank goodness my favorite car has the old fashioned separate v-belts.

So is there a recommended mileage or time when a tensioner should be replaced? I really don't want this to happen again.