You are a brave soul to go out on Black Friday! I wouldn't face those crowds even if they were giving away leathermans!
I went shopping ONCE on Xmas Eve at the mall in Indy. It was HORRIBLE.
There is no real need for a knife when building a shelter, starting a fire, digging holes etc. The only time it's hard to manage without a knife is when detailed precision is needed or when what you can find in the woods isn't strong enough to pry, dig, poke etc.
Well, it depends on what else you have with you and how long you’ll be in the woods. If you had a lighter or firestarter you could start a fire a make a debris shelter or whatever and spend a night somewhere. If you don’t have a firestarter, or will be in the woods longer, a knife is more important. You could not use a knife, and knapp tools out of flint, but that would just make your work harder. With a knife you could make a bow and drill to start a fire.
If you’re in the woods long term, food is important. You can use a knife to make traps to catch food. You can use a knife to make other tools and weapons. Bows & arrows, slings, atlatas, spears, clubs, bolos, etc. You can make tools like spoons and forks. You can make tools to help you cook your food (spits, holders, etc) . You can use a knife to skin and clean what you catch, fish & game. You can use a knife to split wood in wet or snowy weather to get to the dry heartwood to start a fire in poor weather.
It can also be used for defense in areas where there are large dangerous predatory animals in the woods. A knife is one of the most important, versatile tools you can have in the woods, and it is #1 on my list of most important things to carry in the field.
