I rarely see people who drink wine stop at one glass. Very very rarely. I often see wine drinkers have 2 or 3 glasses, and sometimes 4, but it also depends on how much time they have.
I nearly never drink more than one glass of wine in one setting, but I also nearly never drink more than one beer in one setting either, yet on the rarest of occasions, I will have at least two hard liquor drinks in one setting. Strange.