if nobody cares, skip the watchdog
if life or limb is not at risk, use a watchdog
if life or limb is at risk, use a watchdog and everything else you can think of.

There is the true story about the radiation machine? that killed several people because a safety switch was not thought of (often referred to by Jack Ganssle, but I can not recall a name or a link).

Then, on the other hand, there are those over-engineered products that come out too expensive, too late and too difficult.

Erik