>There are definitely dog who will bark continuously for hours.

Oh you must live in my neighborhood. Someone within a several block radius of me has a dog that barks constantly. They let it out around 6 am and let it back inside around 9 pm. I am not exaggerating when I say it barks the entire time it's outside. I've walked my dog around trying to find the source, but I've never been able to pin down an exact address to try and talk to the owners.