Sometimes we decide to take care of confusing tags and this involves manual re-tagging. We all agree that one should only start mass re-tagging old threads after it has been discussed & approved on Meta.
There is a broad consensus that one should not re-tag too many threads in one sitting, because all edited threads get pushed to the front page and can become overwhelming or annoying.
I have seen advice (I believe by @gung, @Glen_b, and others) to limit oneself to only a couple of questions (let's say 3-4) at a time. I know patient people (@AndreSilva) who always re-tag only one single question per day. Some others tend to re-tag more. I have recently started to re-tag 10 questions at a time in order to see what people will think about it. I think it's good to discuss it.
What should be the approximate upper number of questions that one should be allowed to re-tag in one sitting?
This assumes that "sittings" are separated by at least half a day. It also assumes that this particular re-tagging action has been discussed & approved.
Please upvote ONE SINGLE ANSWER from below. Please do not downvote any.