And sometimes I need 6 hours in the office to finish the day in a 2 hour blaze of glory

Fully agree! Different people at different moments in their lives have different time requirements. There is no way to make everyone happy with one single standard -- freedom of choice is the best choice here.

What's more accurate as a salaried thought worker (i.e. software developer) would be a cumulative average of the sporadic fits of inspiration I work each week sometimes at midnight, etc.