I guess that is the fastest route - definitely not the easiest, but the fastest 

This happened when I added all the hiking trails. To avoid this glitch, you can change the "Route Types" setting. By default, it uses all available trails - paddling, portaging, and hiking. If you only want it to use paddling and portage trails, change it to Paddle/Portage Only. Usually this does not happen with the hiking trails, but in cases like this, you will need to change the setting.

This setting is also useful if you want to plan a hiking trip and do not want to route on lakes. In this case, set it to Hiking Trails Only.