Interesting question.
My wife and I are empty-nesters, but for nine months in 02-03 we had four foster kids. Despite the busyness, it was during that time I was able to finish my first novel, 500 words a night after the kids and wife went to bed. I was able to edit it once through. Of course, my work suffered, as 4-5 hours sleep a night did not refresh me enough to function at the pressure-cooker job I have.
I write less now, not because I have less time, but because over the ensuing years I have learned more and more about the publishing industry and have concluded the chances of success too slim to motivate me to sacrifice to write. Perhaps I'll pull out of my funk soon. And the job is still a pressure-cooker, worse in 2004-06, better in 07 as I've been moved to a training position.
So I spend my noon hours--when I can take them--on writing internet sites, or in research, occasionally in re-editing my novel, or in documenting thoughts for future writing projects when time and motivation coalesce. Evenings I write a little in a journal, and read things I think will help me with writing, be it how-to books and articles or books of the sort I would like to publish. At night I dream my books.
And in all I think about retirement, which is only 9 years, 7 months, and 9 days away.
NDG