I just tried experimenting by dragging the roads according to the arrows in Person012345’s diagram, and while most of the time it works, I still sometimes get a curved road even if I immediately drag diagonally (like with the first diagram). Maybe I’m actually dragging in a pattern similar to the second diagram but with a really small first arrow? Perhaps the true answer is a hybrid of our theories. But even so, each time I get the road to go in curved mode in one direction, the amount of curvature is always the same whenever I move the end-node to it’s final destination.