Very good points, I suspect that programming and other forms of concentrated work will require a phase shift in order to continue a high level of productivity,

Very good points, I suspect that programming and other forms of concentrated work will require a phase shift in order to continue a high level of productivity, and the type of productivity won't be the same. But, as DHH of 37signals points out, people don't typically use their hours well anyway. If raising a child left only two hours a day to work, that's still 10 hours during the week -- as much time as DHH spent coding basecamp and rails his first year. If you add to that time you can spend planning, communicating, and thinking about the problem (to fill the time when you're more likely to be interrupted) you can optimize those few hours even further. So far as I can tell, this is the pattern my mother used while she was caring for me and working her way through journalism school. I had colic. But she'd do her interviews in the intervening time, and she'd collect all the information she needed, and wrote fragments she wanted to include. When she got the chance, she sat down and wrote the whole article in a single sitting. PS: Thanks for being part of this community. I started to read your comment page, and you've contributed many wonderful insights I've had to copy to remember for later :-)