When I did a 3:34 a few years back I had the garmin foot pod with me and it recorded my cadence for the entire trip up. Using that bit of data I discovered that I was walking 75% of the time.
Generally speaking, if you are looking at a 4+ hour time, anytime the trail is not flat you are probably better off walking. Faster than 3 hours and you are running almost all of the time with a few strategic walking spots. Between 3 and 4 it is some mix of the two.