clipping (to my knowledge) will be if you apply it before it falls off.
So if you re-apply CS while CS is up on your target you are wasting the time remaining on the first CS.
It would look like this.
1.000: CS applied
3.000: CS procs
3.500: CS re-applied
Now by re-applying CS 2.5 seconds before CS would have ended you wasted a GCD where CS would have been up. Now when CS falls off the next button you hit will be a dps loss because have you had waited for CS, CS would still be up.
[Today 06:48 PM] Ion:swimming in a natural body of water ISN'T acceptable...it's momentarily tolerable