As an author, I almost always respond to a correction on one of my quizzes. I would say always, but before I worked out how to do so, I made the correction and marked it corrected first, then found the original message had disappeared so that I couldn't respond to it. I still sometimes forget and do it backwards.

As an editor, making a correction on behalf of a long-gone author, I rarely do, unless I need to ask the person who sent the CN for more information, as I am unable to evaluate its accuracy independently.

I would normally respond to a correction as an author, either to explain why I didn't agree or to thank the sender for pointing out something I'd missed.

As an editor, there just isn't time to send a response to each correction. The only ones I tend to reply to are those where a player has pointed out a 'spelling error' which isn't, usually a difference between American and British spelling. This is to forestall potential future, similar, notes.