I'm 100% sure of my dates and I went to 43+2 weeks with my first and then my second was born at 38+1 after SROM at 37+6.
Obviously, people's histories are all over the map, but looking back and tallying the numbers, it seems like the most common experience for those who went over 10 days past EDD is to go into labor 1-2 weeks earlier with the second one, although there are plenty who have the same length of gestation on later pregnancies, too. I also wonder how much effect weight gain and physical activity levels have on it.
Thanks for everyone's replies. Keep 'em coming!