I think we need a 99 percent option.
Thor is pretty much perfect in my apartment, but he still occasionally mis-poops when I take him to my office. And there was that time he pooped in a deli... yeah, definitely not always trustworthy.
I don't count his "poop strolls" where he starts in the right place and finishes 20 feet away. I feel like that's sort of my fault, because with the right diet, he poops nice and fast.
When I was potty training him, someone with a lot of yorkie experience said she'd never seen a single yorkie that was 100 percent.