Kick in as few places as possible.

If you have a long Loop You may need to kick it before starting.
Kick it in a loop that waits and can get stuck defeats the purpose.

The Interupt thing was this the Watchdog out pin one way in the interupt. And set it the other way in main. So both must work to make a pulse.

Never hook it to an address line. If the code runs away it can get kicked as the code runs the addresses. Quite useless.