Up untill a few years ago I worked long hours. With my pups I would get up early and give them a good play. I would then make a safe area in my house with toys, water and food and newspaper and left the pup inside. My backyard was too big and dangerous to leave a young pup all day and also people had been known to take puppies from backyards.
I would try and get home for lunch but this wasnt always possible. My first pup I did leave outside without problem but that was a long time ago and I wouldnt do it these days, not where I used lived anyway.