I most want routing when trying to get past a city or group of cities linked by sprawl. I always hope that GPS can help me sit in traffic less and still not use freeways.
Here in the eastern U.S. roads tend to go to the major cities. I'm usually looking for a 2-lane bypass, but any bypass will do. The GPS can help me link together shorter 2-lane roads to get to my destination. Unfortunately the routing software looks for longer, straighter roads.
The routing software on my nuvi tends to select either roads that go through every stoplight in every town from here to wherever OR select all-freeway routes. This is both the reason that I often ignore its recommendations AND the reason that I ask on ADV about routing options -- I know that the data is available and the logic can be easily programmed.
When I'm riding without a destination -- as you said you ride -- turn-by-turn is off although I may still have a map displayed.