I am reading a book titled Daily Rituals: How Artists Work. It's interesting. As you would guess, the routines of each artist vary greatly - from Mozart to Voltaire to Jane Austen. For example, Thomas Wolfe wrote at midnight until the late hours and always naked. Thomas Mann wrote strictly from 9am to noon.
It is Anthony Trollope's routine that most interests me. He produced an enormous amount of writing - forty-seven novels and sixteen other books. He did it while holding a full time job as a postman, and he did it spending solely 3 hours a day writing. He says in his autobiography:
All those I think who have lived as literary men--working daily as literary labourers--will agree with me that three hours a day will produce as much as a man ought to write. But then he should so have trained himself that he shall be able to work continuously during those three hours--so have tutored his mind that it shall not be necessary for him to sit nibbling his pen, and gazing at the wall before him, till he shall have found the words with which he wants to express his ideas. It had at this time become my custom--and it still is my custom, though of late I have become a little lenient to myself--to write with my watch before me, and to require from myself 250 words every quarter of an hour. I have found that the 250 words have been forthcoming as regularly as my watch went. But my three hours were not devoted entirely to writing. I always began my task by reading the work of the day before, an operation which would take me half an hour, and which consisted chiefly in weighing with my ear the sound of the words and phrases. I would strongly recommend this practice to all tyros in writing. That their work should be read after it has been written is a matter of course--that it should be read twice at least before it goes to the printers, I take to be a matter of course. But by reading what he has last written, just before he recommences his task, the writer will catch the tone and spirit of what he is then saying, and will avoid the fault of seeming to be unlike himself. This division of time allowed me to produce over ten pages of an ordinary novel volume a day, and if kept up through ten months, would have given as its results three novels of three volumes each in the year...
I venture to say this perspective could be applied to programming. I've personally never found much more than 3 truly productive hours of programming possible in a single day. The remaining hours are spent trying to get into that 3 hour "zone" or browsing the web.
Imagine if a programming life could be built around this perspective - or a team, or an entire business! But, of course, what made this possible was self-discipline - and that is a difficult trait to learn. 
 If self-discipline was possible, you'd still be left with the problem of measuring output - lines of code being an undesirable measurement of programming quality. I'm not sure what an appropriate measurement would be.)