Let's face it, we're both being kind of sloppy.
Unless his partner is unemployed or a "housewife", there are childrearing and housekeeping tasks that are certain to occupy the "work" time on the weekends. Until the kid gets is own job and (if you live in a place with poor-to-nonexistent public transit) can be trusted with a car, having a kid is work.
> So it's half of 5/9, or simply 5/18. Which doesn't sound that bad compared to 2.5/18 which is what a 1-hour commute gets you.
No, it still sounds bad. A two-hour commute kills half of your leisure time every work day. A one-hour commute kills a quarter of the same. In both cases, that's a lot of time to lose.