I'm not sure that high of a percentage is the norm.
I could tell some stories. I'll give you this one. I moved back from the US to the UK, and the first job I had was with a small IT business in London - 30 employees. Working long hours has never been a problem for me, but these guys were on another level. They'd do a lot of business in the pub, and those drinking sessions would go on into the early hours. Day after day. They'd be drinking all that time, but be back at work, promptly at 8:00am ready to do it again.
I stayed with them for three weeks, but by then I was really feeling it. One evening I pulled the guy who hired me aside and said, "I don't know how you guys do this, the long hours, the alcohol, and back the next day. I'm really struggling." He simply smiled, put his hand in his pocket, and pulled out a small bag of powder. He handed it to me with a smile and went back to his drinking. Needless to say, I quit soon after.