This rules applies only for those waves where 3rd wave is extended . I will talk abt 1st and 5th wave extension and LD's with angles with examples in future . Now when ever u see a 5 wave structure draw a line joining wave 2 and wave 4 . If the impulse has to end then the 2-4 line will be broken in lesser or same time than it took to form wave 5 . And it should reach the minimum retracement of previous wave 4 of one lesser degree in the same or lesser time than it took for wave 5 to form . Regards