I generally plan on making between 1.5 to 2.0 mph going uphill on reasonably well graded trail. My downhill speed on similar trail is about 2.5 mph. On level trail, I tend to average a bit over 2 mph. These are rates that I know from experience I can maintain without needing to stop to rest. Again, from experience, I know I can sustain a daily mileage between 10 and 15 miles per day for several weeks if I wish. In rougher terrain and on steeper terrain, my mph and daily mileage drop markedly. I hiked ths JMT last summer in 21 days for an average of a bit over 10 miles per day. I'm in my late 70's.