It's actually fairly common (in my area, for example, it's common for the controller to tell you to follow the interstate for awhile, and it works especially we

It's actually fairly common (in my area, for example, it's common for the controller to tell you to follow the interstate for awhile, and it works especially well at night). Keep in mind too that just telling someone to fly a certain direction is insufficient - the controller is trying to maintain separation among aircraft, so they need you to follow a particular path through a volume.