Hi PB.
It is always a good idea to play with the “curviness” option. Sometimes it depends on the area you are riging, which fits better. The (Pro-)App has an option to “show all curvy routes” at once.
To tune the route, place waypoints in the middle of the road segment you want to ride.
It may make sense to split the route into two routes - a fast part, and a curvy part.
There is a feature request to do this in one route .
Use of different routing profiles within one route
If you like very small roads like these Swabian Jura Side Roads - Schwäbische Alb Nebenstrecken you may try “Extra curvy” + “Avoid main roads” 
Best,
Manfred