I have used a number of GPS devices over the years to find my way while driving. I won't mention the brand names but there were three different manufacturers, plus two different apps on my phone. They all claim to find the fastest route from point A to point B, but they all tell me to go a different way.
Sometimes, they don't get me where I need to go at all. I usually figure this out when I see the "Welcome To Kenosha" signs! There can only be one "fastest way" to from A to B but they all seem to calculate that route just a little differently.