Hi JDSwoop. Imprecise routes can occur for a variety of reasons, but it's usually the result of GPS data (Automatic depends on your phone for its GPS capabilities). Check out this FAQ for more details.
If you're regularly experiencing imprecise routes, be sure to send the date and time of the trip(s) in question to firstname.lastname@example.org or report it via the "Report a problem..." button found in the Settings menu of the app. Our tech support team will then review your account and provide you with additional info.