I might skip him for a day or so, not for any particular health reasons, but so he does not become bored with it. I had a hard keeper once that would destroy a wood house in a day, a plastic barrel would be chewed down one side in a couple three days and a root did not stand a chance. He dug a hole deep enough to bury a man. I eventually tried a car tire. He fought that tire what sounded like 23 hours a day. With the tire in there the wood house was safe. He lived to be 11. I could not say whether the tires took a couple years off or prolonged him by ???? because he was not eating wood, plastic or roots. I can't see any hours on the kong as long as it is in one piece afterwards. EWO