Some posts can at times have several follow-up questions, sometimes a couple of follow-up questions on the same day.
All this brings us to the question of Can there be too many follow-up questions?
When does the follow-up questions become "too much"? What makes it become too much?
Related: What you may and may not do after receiving answers and How to post a follow-up question?
The problem is not the number of follow-up questions. The problem is the rate of posting them. If you post a follow-up once a week, probably nobody will even notice. As long as it's well done, for example by following the great tips in this other discussion.
Posting follow-ups too soon is not good for anyone:
Posting too fast is not good for you. Given enough time, you might receive opposing, conflicting advice on the same question. If you accept a sub-optimal suggestion too fast, you waste your own time. Better to give it a few days, let multiple answers come in, each addressing different angles, and combine them all together once you have a better overview of multiple aspects and considerations. Also, in the example in question, many of the reviews on later posts would have applied to the first, given enough time.
Posting too fast is abusing the community. You may end up dominating the front page, and crowd out other questions, which is just not fair.
Posting too fast messes with the reputation system:
Posting too fast, too similar questions, can be confusing to reviewers. The thing is, the questions in the example have common parts, which can be "attacked" in multiple revisions. Which revision should I address them? All of them? (REPZ!) It's a mess.
Posting too fast, too similar questions, can be boring to reviewers. In the example above, I reviewed rev2 and rev3, and lost interest in reading further. It's just not interesting anymore. It's better to keep the site content interesting.
Lastly, the poster of the example series has received really a lot of attention. Lots of good answers by a high number of distinct reviewers, including many regulars, over a very short period of time. This is clearly not usual, and not normal. Most questions don't enjoy such popularity, and not because they are of lesser quality. The reason this question received so much attention was because it was unusual activity. This incident sets a bad precedent if we don't step up against it. I think it was not intended this way, but the outcome is an abuse of the site.
The only logical point at which a follow-on process becomes too much, is when the code becomes a duplicate of previously posted code.
Follow-On questions are important on this site, they add a lot of value as they often lead users through a progression of steps resulting in great code.
My experience is that, when a particular user takes their code though a series of follow-on questions, I start to lose interest if there's nothing new to say, so I simply look at other questions, and then, later, see that there's been a new answer, with a different perspective, or insight.
I don't see there being a limit to having "too many follow-on" questions, and, having a 'dangling', unanswered, 'last item' in the chain, is not a long-term problem. Someone will come along and answer it, sometime.
If you are concerned about this as a problem, it may be more because some people who post lots of follow-on questions are also the people who don't apply previous suggestions to their code, so are not improving their code in certain ways between questions.
I find people like that to be frustrating, but there's nothing technically wrong with people who don't follow the advice they are given... I just start ignoring them... if they ignore my suggestions.... and move on.
On the same day? Depends on the substance of the question and of the answers received, but as a general rule of thumb I'd say... one... but that can't be carved in stone: it depends™.
There simply can't be a hard limit.
But flooding the front page with several very similar questions where all but one are marked as answered, is eating up other questions' visibility: the front page can only ever display X many questions.
It's a matter of balance, common sense, and respect of the community: we get more than enough questions daily to get an older version off the front page - waiting at least a whole day between revisions has a number of benefits:
Considering that some follow-up questions can get massively down-voted, I think the answer is Yes, there can be too many follow-ups (at least in a certain amount of time). I say this is based on my observations of community reactions to certain follow-up posts.
Now, I have no intentions of introducing a fixed limit for follow-up questions, but I want to provide my thoughts about what leads to follow-up questions being down-voted, and what question askers can do about it.
A comment on the fifth version of a question said:
Asking 5 reviews of very similar code with very few differences in one day is too much. You aren't giving time for people to answer your questions properly before you ask a new one
This comment has 15 up-votes.
When making follow-up questions, I think it is important for the question asker, and potentially for the voters, to keep some things in mind.
I think the answer to the question Is code ever clean enough? is also Yes. After all, most questions on this site don't result a follow-up. At some point in time, I'd highly recommend just being happy with what you have. After having posted a couple of follow-up questions, consider coding some other things and learn new stuff and look back to your code a couple of months or one year later, I can almost promise you that you will have found ways to improve your own code.
Thought I'll chime in here as the other answerer in the downvoted revision 5 question...
To be frank, I was hesitant about answering that revision initially, as I do not know if another answer is going to come in minutes/seconds before mine, followed by a revision 6 in an hour afterwards, which may not include my newer suggestions. In some sense, just like working with library APIs, I don't think it's too wrong to say that we prefer working with a stable question such that people volunteering their advice here knows that it will remain useful and applicable for some time to come, even if that's going to be just "24 hours".
I also think that we as much as we welcome iterative reviews, we will also prefer those where it showcases additional self-improvements from the OP, instead of mere regurgitating of improvements suggested by others. The latter is easy for anyone to see, but the former is the one that is value-adding for both the OP and for the larger community.
Another more technical way to address is to consider each question as a "commit" on your choice of DVCS. This makes sense after all, since the question is supposed to work well to the best of OP's ability and commits are usually done on working code. If your commit style is a per-line basis, then... good for you. Otherwise, treat suggestions from one (iterative) question to another as the basis of a new "commit", then think about how much further it can be improved by oneself to finalize the "commit" before posting the next iteration.
Why would a user direct his attention to an earlier rev of a question when that was marked with an accepted answer and linked to an open "follow-up"? Either desist in chasing the update links and choose another question or look at the latest to add there...
Honestly I was told to accept an answer and post a follow-up, it wasn't my idea. I wanted to edit the original question and append code to it. I was told not to.
