In my experience, you need at least 2 stops - 1 to indicate the start and 1 to indicate the end. All of the "stops" in between can be set to waypoints. I 've used this method to create a few garbage collection routes. I haven't tested the app a vehicle yet though and wonder what happens if the driver makes a wrong turn (I imagine it will not re-direct properly to get them back on the correct path).
When you set stops to waypoints, does the turn-by-turn directions still speak the "stops?" We like the voice to say the turns, but for garbage pickup, it's really annoying having it say every stop.