17 hours a week at college (term time only), plus assignments and learning for exams almost weekly, and technically 20 hours at work (year 'round) but it's shifts so there have been weeks when I've done 60 hours, but also weeks when I've done nothing, and still been paid the same - it has to balance out over the entire year.
Also have 3 children, 1 primary, 2 secondary.
Also do most things around the house, not everything and kids also pull their weight.
DH does 40 hours technically but is in an odd situation which means its 35 hours in the office and 5 hours he has to find to log from home without a project to work on...
So IMO I do more. He earns more, typically (I took almost 10 years out with the kids, though I always taught a few hours of evening classes and only had a year or so of no income at all when DH used to work away a lot).
37 hours plus assignments and study is far too much in many ways, especially as it sometimes works out as a lot more work hours - my free time is often when the kids aren't free and I'm a terrible procrastinator with my study, which is my own fault...
I hope when I qualify both DH and I will do 30-35 hours.
Work to live not live to work, although we both enjoy our jobs.
How much is enough and how much is too much is a how long is a piece of string question, but I don't think either parent should do much over 45 hours p/w regularly with kids personally, being a workaholic is self indulgent on the part of either parent unless it's essential to put a roof over their heads and food on the table.