After hike route is not right

I expect that I should be able to turn on navigate without a route and put my phone away and see/save my route when I get back.  But large parts of my route are missing. It only seems to hit at certain points and some are totally incorrect.  See image of a test I did in my neighborhood.  Blue line is the route I walked, red line is what recorded.  What can I do to make it work correctly?  My signal should have been fine.