My husband's a Cub Scout leader. I'm a Brownie leader. I lead a Bible discussion at church during the classes 3 of the children attend. (I read all the time, but I can't take classes with a nursing baby!)
You're right, there are hard choices to be made, and if I'm ever at home at the same time as my husband, we'll have to discuss it :-).
I can't imagine how it would be to raise seven kids, especially where we live in California. We home school, btw, so that's yet another way to leverage time.