there is no real set formula, at least not in terms a scientifically 'proven' equation if that's what you're alluding to. it's an animal, not a piece of machinery that can only function under a particular set of circumstances. it would make just as little sense to tell dog owners that black labs can only be given two cups of dry food every morning across the board no matter what. you appear very quick to come down on the people freely offering you advice. good advice. as noted, there is no one correct way to keep ball pythons. rather there is a font of good information that has been arrived at based on experience and observations. some of the responses you've received in this post that have perhaps put you off can be attributed to your ostensible unyielding demeanor. it's fine to take advice with a grain of salt, but you seem to be very demanding. try to be a little more amenable to what you've been told, especially by the moderators, even if others come off as antagonistic or pedantic.
as for the feeders, again it is variable. many people feed various sizes and with changing frequency depending on the circumstances and on what they have determined works the best for their set-ups and goals. certainly power feeding is to be avoided, but there is no 'formula' because no two snakes are exactly alike. the formula also changes throughout the life cycle. young hatchlings can be fed 'appropriately sized' meals every 5-7 days. fully grown adults may not need to eat more than twice a month. as a general rule, 10-15% of the body mass, avoiding anything that is larger than your snake at its midsection, is good advice. the frequency is largely left up to you. you can feed almost any ball that is willing every 7 days without worrying. some snakes also go on protracted hunger strikes for months but remain healthy. if your personal goals are not breeding and simply to own a healthy snake, you could feed once every 10-14 days given how old your pastel is. either way it's up to you.