Setting: Human beings, futuristic, planet terraformed to roughly Earth-normal standards.
My MC is an applicant for an elite military unit. The biggest challence in the qualification process is an extended solo trek over a very long distance and period of time.
Keeping in mind that this is a challenge meant to weed out all but the most motivated and physically fit candidates, what kind of daily mileage could an above-average human keep up for about 140-150 days across reasonably level terrain (as in, no mountains, minimal water crossings, some broken terrain)?
Searched by: "Human Endurance", "Long Distance Hiking", "Long Distance Running", "Trekking", "Forced March".