It has always been part of the original rules , if you look at their example , you may notice that the target never drops below the initial target as layed out .
E.G if the target is say $60 & we have only got $30 of it, it resets to $60 again , as you may have thought $30.

The reason for this is that it takes a lot more resourses to get the extra $30 .
You will find that the first half of the target is a lot easier to acheive than the 2nd half of the target.

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Cheers.