When I was in the military I usually had a large fixed blade (Gerber BMF, Gerber MKII, Tom Mayo combat knife, etc. depending on the job at the time), a multi-tool (LM Survival Tool, Super200 or Wave, SOG Paratool, or first year Gerber Flik-like multi-tool which quickly broke), and a pocket knife clipped into both front pockets (Spyderco Military, Spyderco Police, Gerber Gator, Gerber EZ Out ATS-34, Benchmade AFCK, etc.) and then I had a SAK in my pack (Ranger or Champ).
When I was mountain guiding full time (for 12 years) weight became everything and I greatly paired down the knives I carried. I would be gone for 6-9 months of the year in the back country and my pack rarely weighed less than 60 lbs. (all those shiney pieces of aluminum and pretty pieces of nylon used for climbing add up, especially when you're the one leading). On my harness I used to carry a Spyderco Clipper or Remote Release, then later replaced it with a smaller, lighter and easier to see lime green Spyderco Jester full serrated knife (emergency knife for cutting rope or slings, clipped to the back of my harness where it could be reached with either hand). In my pocket was a Spyderco Military Model and in my pack was a SAK German Army Knife (GAK). The Jester was only for emergency use, the Military was mainly for self-defense (plus I don't feel comfortable without a knife clipped into my pocket) and the GAK was for everything else. At base camp I had a Kershaw Blade Trader with a large variety of blades (paring, chef, fillet, wood saw, bone saw, etc.) for food prep for clients. I used the SAK for everything and in emergency situations, which there were many, was used for shelter making, wood prep and fire making, etc. I was confident I could do everything with that knife and did, although a good fixed blade, a saw, an axe, etc. often would have been a much much better alternative.
But here's the thing: as a mountain guide I was often way above tree line, so wood wasn't alway available, meaning I didn't always have the opportunity to build a fire and shelters were often snow shelters or made of stacking stones and sitting on my ropes for insulation (even at 40 degrees below zero fahrenheit), so a heavy dut fixed blade wasn't "as necessary". I wasn't a hunting guide so I wasn't processing game (sure you can do it with a SAK, but it's messy, hard to clean properly and more difficult to do than with a fixed blade, saw, hatchet, etc.).
Situation, terrain, climate, weather, etc. dictate what you bring. Was anything other than a SAK necessary? No, but it would have been nice a lot of times to have had more. At -40 degrees dexterity is difficult. When hypothermic (which I have been multiple times, at least once a degree or 2 off from death according to the docs), manual dexterity is nearly impossible. This is why I chose a SAK with a one hand opening blade, as it makes it easier to open. I will argue that a GAK is nearly as easy to open as a fixed blade, and if you can't open the GAK then you're probably so far gone that you won't be able to grip a FB also or so far gone mentally that you won't be doing anything right, so maybe a knife is not the best thing for you to have in your hands. To defend fixed blades though, if I had known about Moras back then I probably would have brought one, as they are so light and I love my 510 for weight and space savings.
Now when I'm out and about I wouldn't be without a good sturdy fixed blade. I also prefer to have an axe / hatchet / saw with me, as it makes life easier. I also have 2 or 3 folders with me, whether they are a pocket knife, multi-tool or SAK. I could do with less, but I don't have to now, so I don't. When I teach a survival class I always have a fixed blade, usually a Mora now to show the students that it's more about HOW you use the tools than the tools themselves. For some reason the uninitiated tend to fixate on that super expensive custom knife on my hip and seem to believe that it's the magic talisman that will bring them back alive. I want them to have confidence in whatever tool they have with them, including that $10 Mora, that is more than up to the task.
Plus, this is Bladeforums...we like to play with sharp and pointy things, and that's part of our joy of being outdoors.
