What's too many?

I'm obsessed with TLC and thus am relatively well versed in the Duggar family. In case you haven't heard, Michelle is pregnant with their 19th child. No joke. The oldest is 21. 19 kids in 21 years is impressive. And, insanely scary. I guess now she has a slew of built in baby-sitters though.

I wonder at what point it was like well what's one more? I'm scared transitioning from 1 to 2. Is 2 to 3 bad? 3 to 4? I'm not going to get the far.

What is too many kids? Is there a too many? They're financially sound; much better than most people with no kids or even one child. She's not old - only 36. The kids seem well behaved and relatively well adjusted. (The whole not kissing until your wedding day seems that at least Josh has some social differences though.)

For some people, I could almost argue that one child is too many. Is there a point in which people should step in and say no more?