I've left Sean alone as long as 7 hours though that is not the usual situation. He was fine. It all depends on the dog.
I always remove his harness, shut doors leading to different rooms, and try to make sure nothing will be a problem for him. I leave only soft toys for him to snuggle with or play with. I think he probably spends most of the time napping on my chair since that's his favorite place. (We compete for the use of the chair!)
When I get home he is so excited to see me.

Takes a while to get his harness on since he keeps lying on his back for me to rub his chest/belly. So cute!