When I worked my dogs were left in an outside kennel/shed and run from 8.30 till 5.30. They were fine. And why did I have dogs when I was out all day - because I spent most evenings either at dog training classes or on long walks, our holidays were walking holidays and our weekends were taken up with with obedience shows or days out walking. The dogs were in a routine in the day and it didnt bother them at all.

Now I live and work on a farm so am normally around. Candy is now 5 months and I am just starting to leave her for longer if I am working away from the farm. Up till now I have arranged for a friend or a dog walker to come and let her out if I was going to be gone more than 4 hours but today she was fine with the other dog for 5 and a half hours. The older dog has always been left as long as necessary. She is quite happy being left all day.
My animals are a huge part of my life, I give up a great deal for them but I refuse to be dictated to by them and if I want or have to go out for a few hours it wont hurt them. Having said that I have not tended to go out in the evenings since I got Candy as I havent felt it fair on her. I think possibly we have both been out 3 times since we got her. She was left for up to 2 hours though from the day we got her.