I was the eldest girl in a family of 8 and I can best describe my growing up as abject misery....total lack of freedom because you were needed for jobs and childcare, no privacy whatsoever, no money, (and I don't just mean money for 'nice' things like clothes and holidays...being painfully aware that my parents had serious financial problems), no after school activities, no having friends round because 1. your mum was knackered and short tempered all the time and didn't want any more kids in the house, then also, 2. when maturity / awareness kicked in, realising that you wouldn't invite anyone over anyway because the house you were living in ought to have been condemned it was so overcrowded, filthy and neglected. Of the children my parents had, only half have any children of their own. No one has more than 2. We some of us get on, but it certainly isn't the Waltons and I have huge resentment towards my parents for the totally shit 'childhood' they gave me. I left home at 18, for Uni, as fast as my feet could take me and never went back.
Having said that, I do think that it depends very much on the parents, how effective they are, and how they work as a team. Mine were just a bit rubbish at it all, but I do recall other large families I knew growing up where the kids were happy and looked after, not treated as unpaid help, and the parents both pitched in. That seemed to make a big difference. My father's idea of parenting was to leave it all to my mum, literally. So no wonder she leaned on the older ones... a lot.