Realistically it’s probably neither perfectly concurrently nor consecutively. Concurrently is unlikely but possible, but no woman is fertile long enough to fully raise 6 children fully consecutively. Heck, no woman lives long enough to do that. That’s 120 years not counting pregnancy.
I’m not saying it couldn’t happen concurrently, but probably consecutively.
With the wonders of life-saving vaccines for all, why should mothers need to have so many children to ensure at least a couple lived to adulthood? Oh…
Realistically it’s probably neither perfectly concurrently nor consecutively. Concurrently is unlikely but possible, but no woman is fertile long enough to fully raise 6 children fully consecutively. Heck, no woman lives long enough to do that. That’s 120 years not counting pregnancy.