I've waited to weigh in, but here I am, look out.
20 years ago, I was a 20+ over the limit, get out the radar detector, get me a rabbit and go. I got tickets, I paid tickets, I thought I was the best driver on the planet.
Today, I have kids in the car a lot, or my wife or both, and I see more than I saw back then.
Back then, I just saw highway. Today I see that in many places there are blind entrances, so while it looks like it's safe for 55, traveling at 35 gives more time to react if someone is leaving that blind entrance to the highway.
I have no illusions regarding changing many people's behavior.
However, in MOST cases, the speed limits are set due to some traffic concern. I don't deny that there are speed traps and revenue generation schemes, as we've had such in the St Louis metro Area (St Johns, MO, IIRC.)
So I tend to trust the guys who've set the limits on the roads, because frankly they have a lot more training on how to set the limits than I've had (which is none!)
So my personal policy has been to stash the radar detector. I don't think I've used mine in 3 or 4 years now. I tend to drive the limit in town, where others can freely enter or leave the road, and leave plenty of space between me and the car in front of me. I find that I personally am more relaxed, compared to how I drove even 6 or 7 years ago.
On the highway or interstate, I'm usually no more than 10MPH over the limit, and often I'm at the limit or 5 over.
Here is the analysis for me. For round numbers, let's say the limit is 60. If I have 300 miles to travel, 60MPH will take me 5 hours. At 80 MPH, it will take me 3:45, if I did the math in my head correctly. (3 hours will be 240 so the other 60 is 60/80, which is 45 minutes...)
So if I'm looking at 70 MPH, where I probably won't get noticed by the police, now we are looking at over 4 hours. More math in the head, 4 hours x 70 MPH = 280 miles, the remaining 20 miles will take just over 18 minutes, so let's say 4:18.
Frankly, my peace of mind is worth the extra 33 or so minutes of needed traveling at 10 over, vs 20 over.
I might save that 33 minutes, but if I'm so worked up, what good did I do? How does that impact my relationship with my family? If I'm keyed up, was the cost of that 33 minutes really worth it.
For me, it's not.
For others, it may. I'm not in any way saying my way is the RIGHT way. This is simply the conclusion where I've arrived at this point in my life. My answer may change in the future. If you find it useful, employ it. If not, then I wish you well in whatever you decide works for you.