Zero. I only wrote that for those citing "it's too much of an effort" as a reason not the have kids.

I intended to ask: how many children must I have before I'm allowed to cite "it's too much of an effort" as my reason for not having another child?

The topic is deciding to have kids or not. I doesn't matter how many.

As I understand it, though, the argument applies almost equally to deciding whether to have fewer than $n$ children, whether $n$ is 1 or larger.