That would all depend on the traffic, how fast it is moving, and the speed you're trying to maintain. When I refer to aggressive for the ACC, I'm talking about how hard it hits the gas to return to the speed set. If the difference is more than a few mph, it usually slams the throttle down. The braking is usually never an issue for me, since I keep it set to maintain maximum distance.Wouldn't that have the same net result? If you shorten the following distance, it is going to have to brake more often and/or more strongly.