It depends on where and when. Also on the level of experience. It's usually the inexperienced that head out with nothing at all (no pack, maybe a water bottle at most). If it rains, the temperature drops, they get lost (easy to do with no map), or anything else happens, they're toast.

When hiking in the forest, sun protection isn't necessary. Out in the open, it most definitely is, to prevent skin cancer and early-onset cataracts later in life. I had the early-onset, rapidly-developing cataracts, and one of my DILs had a big chunk of her upper lip removed due to skin cancer last spring, so I know whereof I speak.

We've had I don't know how many SAR calls here in the Gorge just this fall because people underestimated the early darkness or didn't think about setting a turnaround time and were stuck because they didn't take a light.

As for a knife, I use mine (Leatherman Micra) to cut things occasionally, and I use the pliers on it for when I have to adjust straps (because I don't have the strength in my fingertips to pull them through). The scissors, pliers and file get used more than the knife blade, but the blade would be nice if I someday actually manage to catch a fish and want to gut it. Besides, if I need to use duct tape (repair or adhesive tape), I need something to cut it with.

I've never needed the first aid stuff for more than minor cuts, scrapes, the occasional sliver and blisters, but I take stuff for those, especially the dreaded infected hangnail.

Repair kit--safety pins, duct tape and a needle that will hold dental floss (the needle is also for removing slivers and puncturing blisters). Probably not needed for a day trip, but I've used all at one time or another when backpacking. I do not recommend duct tape as a patch for ripped pants, though; it peeled off and stuck to my skin instead. Ouch!

I do take a whistle; it beats yelling, especially when my grandkids are along. Each of them has a whistle with instructions not to use it for play until they get back home. They know about "Help Come Quick" (three blasts) and that two blasts from me means that dinner is ready!

The lists all say "extra clothing" but don't say that the outer layer needs to be waterproof, especially in this neck of the woods. You and I take that along anyway (along with an insulating garment and the sit pad), but you'd be surprised how many don't!

Definitely those "ten" essentials lists are for beginners. I'm sure you take most of that stuff in some form or other along anyway as part of your normal gear. I know I do! But most beginners I see (and I see a lot of them around here!) don't, and unlike us they don't have the skills to cope without it.