Time and time again I have found myself editing existing routes to include bypasses or additional points of interest, and one thing that has always bugged me is that I am always limited by the original waypoints placed to create the route.
For instance, let's say you take a friend's route and want to include a certain road or set of roads. After you duplicate it, you find that from the route they created, they used only a few waypoints to generate the route, and the roads you want to add will require one, two, or maybe five additional waypoints. This means that in order to add what you would like, you will need to delete waypoints leading up to the finish point of the ride before you can add your desired route, then complete the route again with all the waypoints they used. This can be especially frustrating if the route is complicated prior to your duplication!
I suggest expanding the Right-Click options on waypoints to include "Duplicate Waypoint", which will create an additional waypoint just past the point you duplicated from, but the duplicated waypoint will still follow the route at that exact point. This will save a bunch of time on route editing and help people like me greatly!