Well, I have never got one but I am sure I have needed one. I drive the same highways and have learned where the speed changes. And, I know where the major speed traps are in small towns. The very worst road for speeders is The Natchez Trace. Was on that crooked road once when 5 cars passed me. They were going so fast I decided to see just how fast. When I got up to 80, I slowed down. No one and I mean noone should ever drive that fast on that dangerously curvy road. They were still far ahead of me when I got back down to 50. They were between Tupelo and Cherokee, AL.
Most drivers seem to think speed limits are just guidelines.