How does PropertyFinder decide where credits increase or decrease?

1. PF Flex charges more credits where we either provide more value or where we need to maintain marketplace dynamics. e.g. 
1. More credits required when a community provides higher leads per listing, or faster conversion due to high demand, or has an over-supply of premiums leading to lower leads per listing etc.
2. Fewer credits required when a community provides lower leads per listing, or low season driving lower demand, has a lack of supply or lower commission potential etc.