If Jackie was MK Ultra, she could have been programmed to do it.
It depends what time of day it is.
Night shift could last for 5 hours with very few UIDs so there will most likely be a high post count for night shift anons.
It shouldn't be the number of posts that anons make, but the content of the majority of the posts.
It's easy to spot high post count shills because the content of most of their posts is nonsense. And often a lot of quick copy paste.
So censoring by post count alone is not that easily achieved, without considering the content of the posts.
No simple answers to complex problems.