My GSD started sleeping outside of his crate when he was 4 months old but I wouldn't advise that for most puppies, lol. As far as leaving the house though I doubt they'll ever be outside their crates... I've got 4 dogs, mostly I don't trust them to not bicker while we're gone plus we have cats and my GSD thinks they are fun to play with(my cats do not feel the same). It's just to keep everyone safe and out of trouble.
Ollie vom Grunenfeld HIC CGC
Anastasia(Mishka) vom Feuergarten HIC