Its about creating desire via withholding. I realized years ago that the reason some of these girls who see a drop in their number of subs shortly after revealing a new body part is because they made the mistake of making new content of said body part plentiful rather than re-revealing it periodically to maintain interest on a more longterm basis.
The polar opposte problem we face, as subscribers, are the girls that dangle that carrot on a stick for years but never actually reveal anything new. We can be led to believe it will happen sooner or later but as long as they keep getting fat paydays, what incentive to they have to show anything new?