[DJ123]

the issue as you have discovered above is that the algorithm for a scenic route is a national speed limit road which is a single track. The Garmin does have the good option of being able to 'tune' this mode, as you have 3 options for road size; motorway>single track, straight road>really curvy & flat > hilly. It works pretty well once you've fine tuned it to your preference.
Well worth it IMO as it means i no longer have to create a route in 'Tyre' and export. I can let the sat nav do the work now and tweak along the route as i see fit.