Wikipedia:Once is enough

Wikipedia is based upon the written word, and the MediaWiki software in particular is good at keeping a record of those written words. This is particularly important to keep in mind when building consensus, be it for making a controversial article change, deleting an article, or selecting an administrator for the site. Editors who feel strongly for a particular position sometimes fall into a repetitive pattern, saying the same thing again and again in different ways, under the false assumption that the only reason consensus isn't building in the desired direction is because other editors don't understand that point that's being made.

"The truth of the matter? The other editors understand you just fine, they just don't happen to agree with you."

Wait your turn
How do you build consensus if you can only make your point once? You have to wait for someone else to chime in. This means that if you make a change to an article, and another editor reverts it, that you don't do a second revert. Yes, Wikipedia has a three revert rule, but if you're only going to say it once, you aren't going to come anywhere near that.

If no other editor chooses to either revert or make additional edits in favor of your position, then there just isn't consensus for your changes. If you feel strongly about it, go ahead and seek an opinion on the article's talk page. However, once is enough here, too: state your case, and if you get no response, well, you haven't achieved consensus.

Let them focus on your reasons, not on you
One of the reasons why responding to every criticism in a debate is problematic is because it tends to shift the focus onto the editor, rather than his or her arguments. A strident inclusionist or deletionist may attempt to refute every opposing position at an Afd. Similarly, an editor seeking adminship may seek to dissuade opposers by responding to each of their points. Such behavior is considered badgering by some, and annoying by many. It makes the editor appear desperate, which leads to the question, "Why is he or she so intent to getting his or her way?"

Wikipedia is full of opportunities to debate things, but don't distract from your well-formed arguments by assuming other editors will agree with them if they only have a chance to read them again. Many editors with strong opinions only weigh in once on a particular debate, knowing that their arguments are measured on their strength, not on the number of words used to advance them.

AfD
Usually argument repetition in Articles for deletion is in reply to opposing viewpoints. Frequently this increases the emotional involvement of all editors and leads to comments that aren't exactly about the merits of the article in question. Incivility is often close behind, and the closing admin has a lot more irrelevant text to wade through in order to judge the consensus.

RfA

 * Candidate comments. When a candidate replies to most of the opposes it leads to the impression that he or she is desperate to become an administrator.  Some editors specifically consider this a reason to oppose the candidate, while others may be more subtly moved by those comments.  This is compounded if the candidate is addressing the same issue with more than one editor.
 * Other comments. A participating editor in an RfA will often see reasons to oppose a candidate that he or she feels are frivolous, irrelevant, and simply don't mesh with that editor's own feelings.  However, voicing that opinion more than once is generally regarding as badgering, and may actually harm the candidate's chances.  Similarly, if an editor feels that his or her reasons for opposing a candidate are being discounted, it's easy to ask each and every supporting editor if they'd considered that viewpoint.  It's better to assume that they have.

There is no 'I' in 'consensus'
You can't get consensus all by yourself, and if you repeat yourself you're only going to annoy other editors. Take a look at any of the more contentious deletion debates and you're likely to find one or two editors who make it a point to respond to each !vote they disagree with. The same can be seen in the RfA process, particularly when an editor known for having strong inclusionist or deletionist views goes through the it.

It's not necessary to say it more than once. If an editor isn't sure what you mean, assume he or she will ask for clarification. If not, it's better to assume that every editor has read every word of text. Not only does it create a more cordial atmosphere which is unfettered by the tension creating by badgering other editors, it also makes the text considerably shorter and easier to read at the same time. By embracing the once is enough philosophy, you've actually made it easier for other editors to consider your views!

Consensus FTW!