Ty TJ. No reason other than "they" say so, so that makes sense.

While in the Army, I had to do the Expert Infantry Badge a few times. We had to carry 35 lb rucks (packing list enforced and weight checked prior and post march), helmet, weapon, web gear and had 3 hrs to complete 12 miles. And for some reason, they always held it in spring/summer, so you got the full benefit of the lovely NC weather.

Something you may not know, knee high women's stockings work really well under socks to prevent blisters.