Interesting and instructive debate from the first post onwards. The more I read, the more I learned and the more I know, the more I realize how little I actually know.
So as not to just philosophize, the problem of what kind of self-belaying on "normal" trails in the high mountains or where there are already tensioned "cables" with pegs bothers me too. I'm getting on in years, close to three-quarters of a hundred, I don't lack mountaineering experience, I've been mountaineering since childhood, but lately I prefer to go alone, I like to photograph, and as someone already mentioned, also where it can be dangerous, e.g., when you're on the "cable". I got a helmet, now I'm deciding on a safety harness, but the fact that I already wear a "photographic" (some kind of climbing) harness around my waist, with lens and attachments, makes the decision difficult for me.
Since I only lack Razor and stamps around Triglav to complete the transverzale, where I have wandered many years ago, but mostly from the Pokljuka side, I ask for any opinion and advice. Others' experiences are worth their weight in gold, even from younger ones. But I know the decision is ultimately mine anyway.
Otherwise, I'll keep visiting hills and mountains as long as my head and legs serve, of course various "via ferratas" are off.