What I have noticed with zeus and others that i have taked to this goes on till around 2yrs old. Once zeus started chewing up the kids toys,Coffee table he went out to the kennel. Now he is 3 and rarley chews stuff up in the house or yard. You might look in getting him a big red Kong toy. Zeus would chew that for hours. I would put peanut butter in the middle and he woudl chew for ever. I also lost a bark collar to his chewing and replaced the steering whel on my wifes caddy when he was a puppy.
good luck