There is a temptation to try to fix problems by creating new rules to address specific situations. Due to the sheer volume of guidance pages, though, there's a high chance that the intended audience—good-faith editors unaware of any related advice, guideline, policy, or usual social conventions—will never come across the rule until after breaking it. Making new rules is frequently ineffective as a prevention strategy. Instead, seek to preserve or simplify the existing rules, and look for ways to alter process to encourage desired behaviour and discourage unwanted behaviour.
"There's a rule for that" edit
A common reaction to an editor breaking a common practice is "we should have a rule for that". This is reinforced by some editors who adopt a mindset that they are only bound to observe the strict letter of written rules. The Wikipedia community, however, doesn't exist in a vacuum: there are many social norms and conventions that provide a context for community collaboration. For example, in face-to-face conversations, participants can use timely interruptions and other cues to stop one person from dominating conversation, or to provide opportunities for a reticent speaker to be heard. By engaging in these interactions over time, people learn productive modes of communication. It's impractical to try to replicate a global context for behaviour and reasoning with a finite set of rules. Due to the complexities of human interaction, there will always be more cases to clarify. Even if it were done, it would be unreasonable to expect anyone to read them all.
There is a need for rules that are specific to the Wikipedia environment, as well as ones to help establish what commonly-held societal norms are in effect (as there is a divergence of norms in the real world). Before creating any new ones, though, consider carefully if it truly will help address the problem in question, or if it just provides a link target for someone to brandish.
Alternate approaches edit
Having an ever-growing set of increasingly detailed rules swamps editors' cognitive burden and provides more weapons for editors with which to harangue each other. Consider using approaches that preserve or reduce the rule complexity. (Note this applies to content-related guidance as well as behavioural.)
Consider if something really needs to be done edit
Some problems are handled effectively through existing processes and are unlikely to be made better by a new specialized rule. If there is an issue with handling the problem, consider how the process can be improved.
Add a footnote edit
If a widely-held interpretation of existing guidance is contravened by an editor and a subsequent discussion affirms the community view, consider adding a footnote to the existing guidance with a link to the discussion and a concise summary. Don't create a new shortcut to the guidance. This shifts the emphasis in future discussions: rather than wielding a specialized shortcut link as if everyone is expected to know all guidance in every detail ahead of time, you can point to more general, higher level principles, and only refer to previous precedence as needed.
Rework process or higher-level guidance to encourage desired behaviour edit
Consider if the underlying process or higher-level guidance encourages the problem, and brainstorm ways to encourage desired behaviour instead. Although it is difficult to make systemic changes, they can offer a much better chance at addressing the problem effectively.