In Norse mythology, Heimdallr was born of nine sisters. I'm not sure that it took any less time than usual, but I enjoy the story all the same. https://en.wikipedia.org/wiki/Nine_Mothers_of_Heimdallr

Just take a guess at how the baby will be like and get everyone to pretend it already exists for the 8 months (and throw away the experience if mispredicted afterwards) :)

It's called pipelining, and the concept works well in all modern processors. Can also work with people, you only have a initial setup delay :)

No but 9 women can have 9 babies in 9 months.

Which is a 9x output.

Production and development requires multiple parties. This mythical man month stuff is often poorly applied. Many parts of research and development need to be done in parallel.