Boy that's a variable question.

Mind you, those boys in Burma were MOTIVATED! As were the Easy Co. boys.

Personal experience: about 2-3 hours with a daypack in fairly even terrain, 4-5 miles (taking it easy). With Boy Scouts 15 years ago, we could do 10ish miles in about 7 hours, in the Sierra Nevada mtn ranges.

Funny thing though, is I've done 13 mile runs in 2 hours in virtually the same terrain (Mammoth mtn area). The point being, group size and pack weight hugely make a difference.

I figure that the "3 mph" rule is usually a good estimate, unless really mountainous terrain.

In a BO situation, I figure 20 miles a day. Unless I run (go figure)