Map routing

Try using .fit file. succes

Disable automatic rerouting.

U turns are are often a result of misplacing a control point on the RWGPS route - usually a control point placed on an intersection will in reality be positioned just off the intersection.  You can usually look for the U turn error in the RWGPS cue sheet.

Fit and tcx work exactly the same.

GPX will also work the same for "turn guidance".

Turning off recalculation is a good suggestion.

Note the the maps that come with the device are based on Openstreetmap (OSM) data. You might get a little bit better results if you use OSM maps when creating the route on RWGPS (there's a dropdown item at the upper right of the map).

.fit file is te best small sized format. Garmin converts interrally all intoming files to .fit files (see your history and courses file) 

For navigation (what this thread is about),  FIT and TCX work exactly the same.

GPX (track) works exactly the same except it doesn't have course points.

While there usually is no reason not to use FIT files, you might not be able to get the course as a FIT file (some sources will only provide the course as  GPX, which is fine because they all work exactly the same).

Your suggestion to use FIT is not helpful because it misleads people to think there are magical differences. When, in fact, they all work the same.

Yes, FIT files are smaller and what the units use internally but that doesn't matter for navigation.

RwGPS has a standard .fit function

It seems to me that if Garmin is using .fit files in the course and history files and they advise to use .fit files that this a good advise to Garmin users. All file formats are converted in the Garmin Edge devices to .fit files. Reason: efficient file size and therefor better performance.