I gotcha now. I see what you're saying.
I have one who only eats jumbo mice (33g to 45g usually) and day old chicks (same approximate weight). She won't touch rats.
She gets fed once a week (7 day cycle) like everyone else. Two or three times she's gotten two prey items, but normally it's just one. She skips on shed weeks as well.
She's gone from 503g end of September to 852g as of last week feeding that way. One of those mice a week, maybe two if you want, should be more than enough. You definitely don't need to do 20% each feeding.