I'm averaging 3-4% of battery per flight minute over my 50+ flights with the mavic. I usually land around the 25/30% mark, so not too sure how fast the battery live degrades beyond that point, but it's not uncommon for me to hid the low 20 minute mark before I come in to land. If i wanted to fly farther I could stretch the flights out to 25 minutes or so quite easily.
What are the wind and temperature conditions, on average? So far, I have only been able test this equipment between 18F and 45F, and always with no less than 10mph wind.