I think you're definitely right that under the right motivation and for certain bursts of time you can work for 12-14 hours of time, but there has been a good amount of research and studies showing long term damage from overworking and undersleeping:

http://devopsangle.com/2012/04/18/what-research-says-about-w... http://www.forbes.com/sites/daviddisalvo/2012/09/12/why-work... http://www.theatlantic.com/business/archive/2013/12/why-the-...