The leisurely paced 3 hour Martini Lunches are gone (for most). I was surprised though last year on a couple of occasions to see people lounging at restaurants in Chelsea (New York) and looking in no hurry to go anywhere...
As for the drinking, most people will have no more than one and it depends on the group...I once witnessed a business woman making a fool of herself by getting so drunk that she had to escape to the ladies room, not the best reputation builder.
In the winter months, 20 years ago, I had Lunch of Cassoulet or Lyonnaise food with a fellow salesman and we usually drank a bottle of wine with it. The rich (and tasty) food and the wine made you feel sleepy.
In Thirsty Business (on Chow), Christy Harrison expands on these topics in a detailed yet entertaining way.
I dare to disagree with the restaurant server quoted in the piece. He makes it sound like everyone working in the food industry must drink to get through the night. I think it is more prone to create mistakes in the kitchen and service lapses. It is not professional. It does happen.

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