I think a lot of breeds can be left alone all day, as long as they have plenty of toys and entertainment available. The more high energy a dog is, though, the more destructive they are apt to be. I used to have a mini schnauzer, who as a pup hated to be left alone and was very destructive. She matured and did just fine for an entire day on her own. I have a doberman and chihuahua now, and they both do fine all day as well. My dobie has made it up to 12 hours without any accidents and has never been destructive. It has to do with the breed and energy level of the dog, and proper training is really helpful as well.