And it sometimes can vary from month to month. I knew two couples in SF, where the wife had all of the steady income, due to owning bars (which the banks liked when they bought their homes), and the husbands were in constant feast or famine mode due to doing contract work. I'd say, though, that even more than fiscal stability, I think that their situations were even better for their respective kids, since at least one parent could (barring emergency where they could easily pay for care) could be with the child outside of school.