Rizzo is totally trained on piddle pads
Is your little boy neutered? Sometimes un-neutered males tend to go ahead and mark their homes no matter how much training time you put in. Of course so do some neutered ones
Since day one I've been confining him to my kitchen with piddle pads laid out for him. He prefers to pee "on something" so they worked out great for me. Now he gets free roam of two rooms while I'm out, I just make sure to lay down a pad in every room. He is just over a year old and I couldn't be more pleased with the progress we've made considering it's their one and only flaw
He still has accidents in my bf's house, he'll pee right next to a piddle pad so I'm trying to figure out what that is about. I'll probably go cleaning crazy all over that place while he is out of town and then start potty training him for the bf's house. I don't thin it's that uncommon for yorkies to need to be potty trained for every house they go to. They are stubborn little pups, lol
Good luck with your little guy, just know it is possible it just takes longer for some than others.