I've settled once out of insurance.
I looked at the damage (traffic light rear end, basically cracked bumper with a paint scratch), the guy was nice and honest about it. I knew, I will not bother repair it through a shop, since the car was kind of old with other issues. I saved him a ton of money, since he was professional truck driver ....
The above would not have happened, if my car was nice and in a good shape. Once I need to go through with a shop repair, unfortunately all niceties are off, insurance kicks in ... otherwise, it can end up being a mess for you in the end.