Boeira

Don't remember if It is Japan too, but some asian countries tend to count the gestation period for age, so when the kids are born they are around 9 months old.

Each Seal triggers a transformation in the user chackra, certain rythm and pauses can generate different results, they research the changes they want and test possible combinations to triggers the jutsu, don't forget yin and yang percentages on the chackra. That IS my take on jutsu creation.

around 75K per month.

can't be hit by this abomination.