I think the word "balance" assumes equality. Whether it's work/life, or shared parenting, the word "balance" for me assumes that both get an equal share of time and effort.
For me, this never happens. The pendulum swings back and forth. JV is a very involved and hands on parent, but he also works much more than I do, often involving nights and weekends.
I came across this New York Times article about "shared parenting", where couples really do try to share things equally. I found it very interesting and thought provoking. I'm all for shared parenting, but I think it's almost impossible (notice I say "almost"). Take a look at this article when you get a chance and let me know your thoughts: