But i agree that working less than 8h/day could be really more productive. I also liked the "less stuck for coding" topic as "...it is sometimes hard to go bed without solving some unknown issues, and you don’t want to stop coding in the middle of it..." so maybe forcing themselves to stop could be a solution.
Anyway, i would really like to work 4 or 5 hours a day but keeping holidays and weekends free from work and i think this can only be achieved if you can pay your living with products of your own such as your apps and not by freelancing (i am a freelance and i know it!).
But i enjoyed the idea behind the article and i will try to achieve it one day.