This is why you just need to chill on the highways.
Generally speaking, it's okay to do 5-6 MPH over the limit if you are alone, since this is the "1 point" category. Anything over 9MPH, and you are in the "2 point" category and cops want that because of the higher fine. It's not really worth their time for 1 point tickets, because most likely the judge will drop the ticket, since 5 mph can be argued in the accuracy of your speedometer/radar guns.
However, if you are driving with traffic, you are likely to be able to do 10-15 over as long as there are people around you. If you have a flashy car, body kit, exhaust, rims, riced out spoiler, then you will be picked out of the pack and pulled over.
These don't apply all the time, but I've driven on lots of highways at high speed for extended periods of time (110-130 for hours at a time)
It can be safe, and law-man free if you spot. Radar/laser works on line of sight, and if you can't see more than 3/4 of a mile downrange, DO NOT SPEED. Radar guns are good to about 2400FT, laser too. Also, keep your eyes peeled for cruisers in traffic and hiding in dicky pits, those median turn arounds, and bridges and whatnot.
Also, at night, don't drive more than 10 over, because you can't see well enough, which is a safety hazard.