I know cops use the in car radars in the suburbs.
The point is that if your radar detector is beeping every 5 seconds then your brain wont be switched on when its beeping for a radar.
Hence making it less effective then if it was setup to just detect multinovas, which are much more common.
If you have never been caught by any radars by leaving k band on and can put up with all the annoying beeping then good for you, keep doing what your doing.