I've been slowly working at trying to destroy various moles all over my body. My skin almost always stings (5% Lugols). I put a drop or more on each so that the liquid covers the mole (not a thin smear). However, some of the healthier moles never sting. And the healthy skin never stings—sometimes the droplets run if I'm not careful, or I'll get some spilled on my fingers and will just smear what's on my fingers over my skin somewhere, just to absorb it. During and after the sting, I get an intense itching. Despite all that, the stinging and itching are gone within about 10-15 minutes (only a little longer than it may take for the droplets to fully dry).
My experience with the skin problems that the Iodine is applied to is that 2–3 days after applying the iodine, the skin over that area will get shiny, dry and scale off (I'll often just peel the skin off). I can usually peel more layers off over the next several days. My moles have been getting smaller. I then give things several days to heal up, then I apply more. I'm left with pink skin afterward. OK, I'm a little weird, and have fun peeling the layers off, but it's more the idea that I AM getting rid of the moles.
I have noticed that IF you just keep applying the Iodine after it dries, so every 15 minutes or so, to the same spot, you can get rid of more of the mole faster, but the tissue underneath will need more time to heal in the long run. In this case, you may get a little inflammation and the spot may be a little sore, and a little scabbing. I'm not so impatient to get rid of the moles, so I don't do this often. I may reapply 1 or two times that same day, because for me, that's about right; more will cause the inflammation, etc. I do believe this inflammation though is just part of the healing process.
I did stop for a few months, and the pink areas of my skin finally looked like the rest of my skin. I had posted images of several moles I'm working on in the past, and some day when they are 100% gone I plan to post new images for comparison.
Some moles as I treat them do get a little inflamed, even with just one application, but that's short lived and just says to me there's some healing going on.
For my face, even smearing some of the spilled drops across a cheek, forehead, nose or chin, never got the stinging, itching or peeling skin. Only the areas that have previously "damaged" skin ... probably from moles or sun damage, etc. Some of the moles I'm treating are starting to sting and itch less, too.
So, from my experience, it's not doing permanent damage, but you will have pink skin (like the new skin after a scab comes off) but given time (which may vary greatly for different people, how their bodies heal) will even out with the rest of your skin tones. In your case, you are dealing with such a large area of skin, I'd suggest only focusing on a small patch at a time, or definitely dilute it. Don't overdo it on any area of the body you wouldn't feel comfortable with the potential for long-term pink skin (or possible scarring ... I can't say that won't happen for you, just that that has not happened for me)—best for the face to err on the side of caution. For some people it might be worth it, others it's not.
The itching and stinging are seriously intense, and are about enough I think I'm going to go insane until it goes away. So it IS a big test of stamina to hold off on scratching until it dries. It is TORTURE!!!
I've noticed for myself the Iodine disappears really quickly from the palms of my hands, especially if they're a little sweaty. I've closed my hands into fists when I've had iodine spilled on the hands to try to keep it unexposed from the air and hopefully absorb it (thus getting sweaty palms), and it's gone within about 15 minutes. Painted on my face takes overnight for it to fade, arms and legs 24 hours. I haven't tried painting the soles of my feet yet, because I tend to run around barefoot or wear sandals often and don't want to walk off my iodine. I drink 8–12 horizontal drops of Lugols a day, though occasionally take a week or two off.