I did three quick test routes that I know.
All have errors. All county-maintained roads.
Test2 errors are a glitch in the app.
Test1 & Test3 have errors on about half the miles.
YMMV
Test2 - Montana -
https://ridewithgps.com/routes/37331140
Test1 - Wyoming -
https://ridewithgps.com/routes/37331091
Test3 - Kansas -
https://ridewithgps.com/routes/37331235