I have a pretty basic radar detector (as well as a non-functioning built in K-40 that came with the car) which seems to always picks up the LEO with a radar gun and the cruiser with the always on radar.

The real risk here in AZ is photo radar which nothing picks up in time. Consequently my life is spent both city and highway driving exactly 9 miles over speed limit. The detector is just a reminder. I have driven AZ, UT, CO, NM, MT, WY, CA, TX, LA, AL, TN, MS, GA, and SC, following this 9 mile rule with no incident. The only exception is that for speed limits over 70 mph, the margin is reduced to 4 mph over speed limit (means I go 79 in both a 70 or 75 limit).

This is over decades of driving. Maybe I'm just blessed or lucky but it works for me. Also I do not try this in obvious little speed trap burgs.