Absolutely. To push some anecdotal evidence on top of the heap, my job has a Light side and a Dark side.
When the Light side is in effect, I generally work 8-9 hours a day at my day job (basically until I feel my focus start to drift, or until I'm no longer involved in discussions). I then go home and exercise + relax + cook dinner for a few hours and then launch into my personal project. Every now and then, I'm able to spend a morning or an afternoon writing scripts or elisp programs that will be productivity wins over the long run. All told, I meet most of my deadlines in this phase.
When the Dark side is in effect (around twice a year, lasting for a month each time), I'm on an insane death march for a demo that is slipping. Sometimes it's my fault, sometimes I'm put on one that's already falling behind. My work days are 12 hours, I sometimes come in on the weekends, and I'm bitter 24 hours a day. My diet, exercise, and sleep habits slip. I spend much of the next few weeks refactoring the code that I write in this phase, because when the deadline is fast approaching, it matters a little less that you use a global variable to transmit state. To use a Jeff Atwood phase, I accumulate most of my Technical Debt in this phase: http://www.codinghorror.com/blog/archives/001230.html.
In the long run, I'm not getting any more done in the burnout phase, but it definitely gives me a lower quality of life and a lower quality of software.
When the Light side is in effect, I generally work 8-9 hours a day at my day job (basically until I feel my focus start to drift, or until I'm no longer involved in discussions). I then go home and exercise + relax + cook dinner for a few hours and then launch into my personal project. Every now and then, I'm able to spend a morning or an afternoon writing scripts or elisp programs that will be productivity wins over the long run. All told, I meet most of my deadlines in this phase.
When the Dark side is in effect (around twice a year, lasting for a month each time), I'm on an insane death march for a demo that is slipping. Sometimes it's my fault, sometimes I'm put on one that's already falling behind. My work days are 12 hours, I sometimes come in on the weekends, and I'm bitter 24 hours a day. My diet, exercise, and sleep habits slip. I spend much of the next few weeks refactoring the code that I write in this phase, because when the deadline is fast approaching, it matters a little less that you use a global variable to transmit state. To use a Jeff Atwood phase, I accumulate most of my Technical Debt in this phase: http://www.codinghorror.com/blog/archives/001230.html.
In the long run, I'm not getting any more done in the burnout phase, but it definitely gives me a lower quality of life and a lower quality of software.