It depends on circumstances (e.g. climate, type of housing, the breed of the dog, etc.), but in general, dogs are pack animals who need to socialise, bond and interact with other members of the pack, so surely if you spend most of the time indoors yourself, that's also where your dog should be? Now if you have a house with a backyard or something along those lines, and spend time both inside and outside, then giving your dog the freedom to go back and forth seems to be ideal...