Absolutely, regarding the 5 mile training hikes.
During my two most memorable campaign--meaning marching every day wearing your knapsack or blanket roll, and sleeping far from the cars--events, one of two nights in Tennessee, and one of four nights in Louisiana, I learned the age-old truism that Less Is Best when packing.
I would now leave the spare shirt--but not the spare socks-- behind. I also learned a tin mucket can fit in a Federal double-bag knapsack, preventing it from banging around on my hip all day. I learned a haversack is best used for rations, not as a general purpose man-purse.
I learned a rubberized canvas blanket-gum blanket-is literally a life-saver in cold wet weather at night, and every other night. I carry two of them. One for over me and one for under me. They are worth the weight and space.
And I learned to carry my own "necessary papers" in an easy to reach pocket. Things the real soldiers learned pretty quickly, I imagine.