When I am out in the wild for more than a day I always think about survival. I only want to carry a certain amount of weight. When you are walking around in the wilderness weight is important. You only want to burn the calories you have to and at the end of the day you don't want to be to tired to do want you need to do to set camp and eat. Each survival tool I choose to carry is important. The more tasks they can accomplish is a factor on what to include. Bandanas are perfect. They are lightweight and have many uses in survival situations.
Bandanas are cheap. Because of their lightweight you can carry a couple if you want. I use my bandanas for many things. They are of course great sweatbands and head cover to prevent heat exhaustion. When not on my head I may tie a bandana to prevent sunburn or keep warm in cold weather. I soak my bandana in water and wet tie it around my neck to keep cool. When in camp I Pick up my pot, wash my dishes, and wash up with my bandana.
I have used my bandana to tie items on my belt loop or my pack. I tie my sierra cup on my pack with my bandana. Bandanas are usually a little lighter than those expensive clips and utilizing items from home saving money.
A few years ago I was in a pretty good dust storm and used my bandana as a dust mask. It worked great. Regularly I wrap a stone in my bandana tie a cord to it and throw it over a limb. This is a time savor when making shelters. I have also used my bandana to make cordage. I rarely take a tent, usually just a blue tarp. I can throw a tarp up quick at the end of the day.
I have used a bandana to filter water. There are better filters but a bandana isn't bad and is better than nothing, especially if the water is muddy. I have problems sometimes with my feet on the trail. I usually have moleskin for those hotspots but I have cut up my bandana and put them on those hotspots. Blisters in the wilderness suck!
I use my bandanas to clean my glasses and my camera lens. When I forage for food I use my bandana to hold berries and such.
There have been times when I am out that I have used pieces of my bandana for firearm cleaning patches and wiping them down with gun oil. I have black powder friends that have used bandanas as bullet patches for muzzleloaders.
I have never had to do this, knock on wood, but a bandana makes a nifty sling for an injured arm or wrist. A bandana would make a great tourniquet if needed. You can also us a bandana as a sling to throw a rock at game. I have never done this either.
A few other things I have never done with a bandana but could if I wanted to: Waist Pack, Mark a trail, eye patch, ear muffs and a hobo pack. Bandanas can be used as toilet paper but I am thinking this would be a one time use. People report using a bandana as a signal flag by tying the bandana onto a stick.
For me a bandana is a must have on my pack, in my bug out bag and in my survival gear. A bandana is as important as rope or duct tape. But best of all a Bandanas best use always is to catch a sneeze.