My grandmother had eight children while her other fifteen siblings had none or had less than three. They grew up before Vatican II but soon those fifteen siblings fell away from the Faith.
It is true God decides how many children are placed in each family. But unfortunately, in my extended family, I have seen agreements in frivolous marriages (which ended sorely, and are now in adultery). They even agree with Natural Family Planning, which in today’s society, IS used to prevent pregnancy. Only God knows how many couples actually canceled out three, four, five children He intended to give.