My keyboards have always had an INS key but they’ve never done anything and I’ve never bothered to map them to anything. I do sometimes want to overwrite, but that’s always in Vim where I can enter replace mode.
Hm I've seen keyboards where INS didn't appear to do anything, but that was because you had to press a different button to activate the set of keys that includes INS, and you might have been looking at a case of that.
