Jerk is the rate of change of deceleration. The original settings were a pause of 1s, followed by 5m/s³ of jerk up to 7m/s². That means it takes 2.4s from the issue is detected until "full" braking of 7m/s² is applied.

Even 20m/s³ doesn't seem all that aggressive to me. A good car can brake with around 9m/s² (depending on the state of the road) which means it's going to take 0.45s to go from 0 to full braking.