I would replace them case by case if they appear uncertain.

I just did my timing belt (see my post yesterday) at 125000 miles (first was done at 60000). A dealer service manager advised me not to replace water pump unless it showed some problem. I did replace it because it felt definitely loose, though not yet leaking. I brought the tensioner and roller to the dealer. A tech said the tensioner looked ok and I then tested it by slowly compressing and releasing in a big drill press vise - found no problem. I had my dealer parts man bring out a new roller set and it did not feel any different from mine so I just cleaned and reinstalled it.