Discussions rarely end in "requests for comment". Are you referring to any discussion in specific?
The English Wikipedia follows a community norm called "BOLD, Revert, Discuss" (BRD) in which all editors are encouraged to be bold when updating the encyclopedia. If another editor objects or if it breaks another community norm, they will revert (undo) the edit. At that point, instead of reverting back and forth, which is known as "edit warring", the article should be left in its status quo state and an editor (usually the one who is proposing the change) should start a talk page discussion about it.
Usually other editors chime in there and the point is to find a consensus agreement on including neutrally phrased information that has been covered by reliable sources. Most discussions end this way. One side peters out either for lack of sourcing or lack of interest or because of a convincing policy-backed argument.
Claims very often do stick on low traffic pages. On high visibility political articles, the content has already been so heavily edited over time that most major discussions have already been had, and any controversial change requires more background justification than simply relying on "BOLD, Revert, Discuss". So to your question, in the rare occasion that there is a long talk page discussion, consensus is not measured as a poll or vote but by weight of policy-backed arguments. For example, Reddit brigades a discussion with "votes" in a certain direction, they will not weigh as heavily when an experienced, neutral community member (usually an admin) formally "closes" a contentious discussion after either a week or 30 days. The more contentious the discussion, the more scrutiny is put on the closer to accurately summarize and represent the strengths of the viewpoints presented. Again, discussions rarely reach this level of discussion.
More often, if you and another editor are going back and forth on a talk page, having reached an impasse, the next step is dispute resolution. Usually this entails finding a neutral third party opinion by posting a neutrally phrased request for a third opinion on a variety of related noticeboards. "Requests for Comments" is another option for creating an open invitation. There are also other escalations for behavioral issues.
The best way to break a the uncommonly long discussion with the same voices on repeat is to declare an impasse and try one of those solutions that bring in outside opinions. Otherwise the "discussion" will continue to drone on, producing text but no resolution. If the subject isn't pressing, sometimes another reader/editor will find the stale discussion months later and resolve it then.