SmoothDamp smoothTime ignored!

Hi :)

SmoothDamp.smoothTime is ineffective at controlling the duration of SmoothDamp. Has anyone had success using it?

In the following script SmoothDamp is set to reach it's target in 1 second...it's takes ~2.4 seconds. I know smoothTime is approximate but this amount of deviation makes SmoothDamp useless for a lot of applications.

Chuck this script on an object and and hit play. On the script toggle the 'StartSmoothDamp' bool and the SmoothDamp will run until it's within the defined threshold of the target value at which time it will log out how long the SmoothDamp took.

 using UnityEngine;
 using System.Collections;
 
 public class SmoothDamp : MonoBehaviour
 {
     [Range(0f,1f)]
     public float Current = 0f;
     private float target = 1f;
     public float Velocity;
     public float Duration = 1f;
     private float LastTime = 0f;
     public float Threshold = 0.05f;
     public bool StartSmoothDamp = false;
     
     void Update ()
     {
         if (StartSmoothDamp) {
             Current = Mathf.SmoothDamp (Current, target, ref Velocity, Duration);
             
             if (Mathf.Abs (Current - target) < Threshold) {
                 Debug.Log ("Duration: " + (Time.time - LastTime));
                 StartSmoothDamp = false;
             }
         } else {
             Current = 0f;
             Velocity = 0f;
             LastTime = Time.time;
         }
     }
 }

Thanks for reading :)