What happens if you shorten a chapter in the process of editing, and then add the text back? Are you charged for the addback, or does it work on the basis of the max you've ever reached?
Post work and then delete, no change in cost points or review points. Then you add back, you will be charged for the add back.
So you cut 4,000 words down to 2,000 and reviewers still get credit for 4,000? Then you add 1,500, to 3,500 and you are charged for adding 1,500 even though you're under the original? Do reviewers get extra because you've paid extra?