Ruhlman’s recipes are outrageously high in the amount of culture needed. Marianskis are based on what a whole envelope of culture is capable of producing.
While adding too much culture will not harm anything but the pocketbook, it is unnecessary.
A good rule of thumb is to add 1 gram of culture for the first Kilo and add .25 grams per each additional Kilo. Works for all cultures available to the home producer, like T-SPX and FRM-52.