Google Maps gets it right: it tried to keep you on road, but only for a few tens of seconds. After that, if you are in the middle of uncharted territory, it'll show the marker there.
(This is probably because Google Maps can be used for walking/biking too)
Not that I mind too much, I know how to get around without navigation.
Wish we could put it into a manual mode where you just reset it's position once and then it updates based on wheel encoders & snapping to roads.
You've got it backwards. I was explaining why GPS should take priority over mapping data. Not the other way around.
So that’s the same thing you’re saying
Please don't do that. The map is simply not good enough and does not have enough context (road quality, terrain, trail difficulty) for anything but very causal activity. Even then I highly recommend to use a proper map, electronic or paper.
It has a lot more map data accessible and you can even overlay National Park Service maps, land ownership, accurate cell service grids, mountain biking trails, weather conditions and things like that.
Disclaimer: Just because you see a route on a map, digital or paper, does not mean it is passable today. Or it may be passable but at an extremely arduous pace.