Detectors are good especially if you are in an area you are not familiar with. It alerts you to issues and the obvious response is you slow down. Some towns have roads setup as speed traps. Going 2 miles over will get you a ticket. So it does help with towns that generate revenue from traffic enforcement. Melbourne Beach FL is a good example. The road is a posted 30MPH, they even have a sign before entering the road as to what the speeding fines are going to be!