I think most folks who use GPS don't examine the route carefully before they set out. They just enter start and stop locations and blindly follow the route. When I plan a trip, after doing the above, I zoom in on the route and make changes to it as I deem necessary, such as bypasses or alternate routes.
I DO use Co-Pilot on my tablet and have found it to be pretty accurate. However, there are times it will do goofy things, but having closely examined the route before hand, I make the necessary correction. It then corrects itself.