We just stopped kenneling our 7 month old at night a couple of weeks ago. The kennel is left open in case he wants to go in. I don't trust him to leave him out of the kennel if we have to go somewhere though. I don't know how long it will take for that.
Riley was never kenneled and at 6 months we left him in the house while we went somewhere for about 4 hours. He did poo by the back door, but that is because he could not get outside.
Barkley and Cloey were never kenneled. They have been left in the house alone many times without destroying anything.
I think it depends on the dog.
Riley - 11/05/2012-8/30/2013 (Myasthenia Gravis)
He will always be in my heart.