generally people say inbreeding BPs for one or two generations is totally fine, just dont overdo it.

also there is a way to sort of push the reset button on inbreeding. if the ancestry on the fathers side is completely different from the ancestry on the mothers side, the BP will be free of inbreeding, even if the parents INDIVIDUALLY are inbred.

generally breeders avoid it when there is no real reason to do it, but when it brings a real advantage they go fot it.

also it scales dramatically with the size of the collection. with 20 snakes the amount of possible pairings is rather limited, and the amount of useful pairings is even smaller. with 300 males and 600 females, the amount of possible pairings and useful pairings is so incredibly large that avoiding unnecessary inbreeding is really really easy. large breeders can even start a double recessive project and produce double recessives without inbreeding.