I would suggest that if you cant leave your dog alone in the house that YOU may have some issues with YOUR training.
I would also suggest not taking for granted that your animal will "protect" the house as (granted) we all hope our dogs would.
At under 2 years old she is the equivilant of a toddler. Do you have kids? Are you a bad parent because your toddler threw their food of their plate or spilled their drink? Are you a bad parent because you turned your head for 30 seconds and your kids decided the kitchen table was needed more color then the paper they were coloring on? Would your toddler not cause some mischief if left to themselfs? I have rescued and rehabilited. Several dogs, two of which were faught, and I'm pretty confident in my abilities to train my dog. She is still young tho. You can't change that. Don't question me on my training