Positioning has a lot to do with it. I labored on and off for days before my very large child flipped from posterior, and he was born very very quicky after such.
Though artificial rupture of membranes may 'speed things up' for some women, for those with positioning issues it can compound the baby down into an even more unfortunate postion - which usually then leads to cesarean. My son needed that fluid to help him switch positions.
With birth, its so important not to mess with anything. Any augmentation can lead to a snowball, and turn the slightest thing into a csec.
eta: DS2 was born at 42wks 5 days, and I wouldn't call it 'scary overdue' for me. He was right on time, no signs of fetal distress or placental failure.
DS1 was born 10 days past my due date. He was induced, which was a mistake on my part.