With the exception of a select few cars, damper settings made next to no difference in GT5.
Seems this has carried over to GT6, but without a proper speed test no one can be 100% sure.
1/10, 10/1 was the norm for RWD & 4WD in GT5 supposedly giving better results.
But in most instances the difference was .001, hardly worth the effort adjusting them.
Edit: campers aren't in this game. That would be COD.