It's safe to say that 4 miles is the average you'll run per day, but keep in mind that you'll have the "O" course, "Endurance" & "Stamina" courses and a few others. Which means you'll have other activities to accomplish other than your run, per day, and.....running with rifle and 782-gear.
And then, there are....HUMPS!! ahhhhhh yes, Humps
Just make sure you really break your boots in and get all your blisters out of the way at home. Now that you can run a good PFT, do it in "boots and Uts". The "E" and "S" courses are done in boots and uts, rifle, and 782-gear. I don't remember the exact distances, but its something along the lines of:
Endurance Course -- 2.something miles with lots of obstacles
Stamina Course -- 3.something miles with just over a mile of obstacles
And my last "2 cents" are: Know your Op order and be able to write out the skeleton in less than 2 minutes.
The end
"You forgot your fortune cookie"
Dirty Harry