[quote who="eX^" reply="15" id="2188975"]Where is this statistic? [/quote]
Read the presentation, there's studies and articles referenced within, it's pretty accessible.
[quote who="eX^" reply="15" id="2188975"]I personally work better at late nights and staying up til early morning. [/quote]
That's not what you were talking about, you were talking about extra hours. I've seen plenty of projects go down the crapper because people think they can just crunch until the problem goes away and that's simply not the case.
You get 3 weeks of boost and then a long tail of below average productivity that causes it to either even out or give you slightly less overall productivity.
As mentioned in the presentation, one of the biggest problems with extended crunches is that people FEEL like they're being super productive, but really they're just making a lot of haste to achieve very little speed. It's no good finding the fix a day earlier if you make mistakes and add enough bugs to cause another week of work