[jtheory]

But -- after 6 months the parents' level of expertise is significantly higher.

I have two kids, 3 and 6. The second was hard, but we knew what were getting into, largely, and how to survive it. The first was... rough.

I'm not sure about sleeping through the night stuff -- we did the co-sleeping thing, which helps a lot! But still, by 8 months I'll bet the parents would have some strategy in place -- maybe "hey, tonight's your night to wear earplugs" coupled with strategic naps.