Faith, we called our first modern dog, Daisy,a "stealth pooper" and would do what Zeke did. We got her at 8 months and I think the previous family hadn't trained her. Linda taught her what was expected in about two weeks, but for quite a while she'd still go "on the hoof."
A week ago Linda found a Yorkie-Poo from a reasonably close family. We're calling her Skye. She's only 9 weeks but figured out a pee pad on the second introduction, as long as it's in sight or smell range. As is true for most puppies, she's training US to make sure she's in the right place at the right time. But a Yorkie's digestive tract is so small it's very predictable.
Her running speed is just about a moderate human walking speed, so your idea might be spot on. Skye has a habit of inserting her feet UNDER ours while walking around, so we are having to be very careful. I'll message you a link.