I opened a ticket with Garmin Support on a issue I have with a route that is prompting for turns at locations other than the ones I have added to a route drawn on RWGPS.
Here is what I was told to do for the issue.
If you are using a route with pre-loaded turn directions then I would recommend changing the activity type under "Navigation" in the Activity Profile to "Direct routing" as this will tell the Edge 810 to rely solely on the route information and not the mapping and routing preferences. It basically completely turns of the automatic routing options on the device.
I will be testing this next week on the route I have been having issues with.