It removes the human error of timing the two clicks. It guarantees that the shot lands exactly when the accuracy radius shrinks to zero.
In this example, the script is bound to Mouse3 (pressing the scroll wheel). When you click it, the script zooms and fires instantly. Why Use a Fast Zoom Script? Cs 1.6 Awp Fast Zoom Script
Players often add these lines to their userconfig.cfg or autoexec.cfg files: It removes the human error of timing the two clicks