I find creating a route on the device takes far longer than doing it on my laptop and transferring it. Obviously if I just want to get to my destination I can do that directly on the device and use the routing preferences to take me along the sort of roads I prefer. So, for instance, A to B in the car I would probably use motorways just to get it over with. Mostly I use the bike for pleasure so I prefer to use more interesting roads . In that case I plot the route in Mapsource so that I am making the routing decisions and not the device. I simply enter my start and end points, let Mapsource suggest a route and then drag and drop until I am happy. My start and end points are waypoints but everything else is usually a via point. Occasionally I might add a waypoint on the route but only when it is somewhere I definitely want to go, say a cafe where I have arranged to meet friends.
On the subject of problems in navigating to the start of a route from another location I find that if the "start" point is a waypoint the device simply navigates me there (using my preferences) and then carries on with the planned route without altering the route in any way.
John