I didn't read the whole thread. As a police officer myself, in order to get through the academy, you must be within 2 mph to get certified to be able to use radar/lidar. I have wrote many tickets just based on estimation of speed. I only write tickets on those I feel are really going super fast on an estimation.

Sometimes you can't get your radar locked in when there are several cars in multiple lanes, so you can visually estimate the speed.