A leash is a good tool for inside if you are having problems with housebreaking, but I have never needed to do that. Do you use a crate?
Or is it just outside -or- inside on a leash? My goal is to have a total trustworthy dog in the house. I have accomplished that with every dog I have housebroken.
And by free time, I do not mean unsupervised. I always watched my pups like a hawk, but they were free to play, not just be tethered.