Most of them are folklore. A small number are real, and they are almost never the ones people spend their evening worrying about.
CV advice has a particular problem: it is passed down rather than checked. A rule gets repeated because it was repeated, and it survives long after the reason for it stopped existing. Some were never true. A few are true, quietly, and matter more than everything else on the list combined.
Full disclosure before the sorting starts. I worked as a recruiter, at a staffing company placing blue-collar roles, and interviewed for administrative positions. That is where the interest in this comes from, and it is not high-volume corporate screening, so I am not going to lean on it as though it settles anything. Everything below either follows from how hiring actually works or points at the research, which is linked where it exists.
The rules that are real
Make the basics findable in the first few lines. This is the only rule here that is close to absolute. Current title, current employer, how long you have been there. Eye-tracking research on recruiters puts the first pass at a CV at somewhere around six or seven seconds, which is not enough time to read prose but is enough to find a structure. If a reader has to hunt for the basics, the hunt is the whole first impression.
Say what you did, not what you were responsible for. “Responsible for the onboarding process” tells a reader that a process existed and your name was near it. “Rebuilt onboarding so new hires were productive in their first week” tells them what changed. The first version is not wrong, it is just invisible, and a great many CVs are written almost entirely in it.
Use the words the posting uses, where they are true. Not to feed a keyword algorithm. Because the person searching an applicant database is working from the same posting you are reading, and they type its vocabulary into the search box. If you call it “client retention” and the posting calls it “customer success”, you can be a perfect match and never surface in the search. This is the practical core of what gets sold as ATS optimisation, and it is the part of it that genuinely works.
Be consistent about dates. Not because software rejects inconsistent formatting, but because someone checking a timeline reads inconsistency as carelessness, and a CV that looks careless invites the guess that the candidate is. Same format everywhere. Nothing clever.
Send something that was clearly made for this job. A CV that visibly answers the posting reads as effort. A general-purpose one reads as a mailing list. Tailoring each application is the rule with the largest gap between how much it matters and how many people do it.
Five rules. That is most of what actually moves the outcome.
The rules that are folklore
“A CV must be one page.” Imported from US graduate hiring, where it made sense, and then applied to everyone. If you have fifteen years of relevant experience, compressing it onto one page does not demonstrate discipline. It demonstrates that you were following a rule. Two pages is ordinary for experienced hires. The real rule underneath is that nothing on the page should be there without earning its place, which is about editing, not page count. A tight two pages beats a cramped one page and beats a padded three.
“Never leave a gap unexplained.” Gaps are ordinary, and the panic about them causes more damage than the gaps do, which is a whole article on its own. The short version: a visible gap is a question, a disguised gap is a problem.
“References available on request.” Everyone already knows references are available on request. That line stopped carrying information decades ago. It is not harmful. It is a line of space that could have been a fact about your work.
“Start with a career objective.” Telling a reader what you are looking for was useful when a CV arrived by post without a covering note about a specific role. You applied to a specific posting. They know what you are looking for. A short summary of what you actually are is worth the space. A statement of what you want is not.
“Never use a two-column layout.” Modern parsers handle columns. What actually goes wrong is putting critical information inside an image, or in a header or footer, or in a sidebar so narrow that the reading order stops making sense. That is a layout problem, not a column problem.
“There is a right font.” There is not. There is legible and illegible. Nobody is being sorted out of a pile over Calibri versus Arial, and whoever says otherwise is usually about to sell you a template.
“Never send a PDF.” PDFs have parsed fine for years. The one real exception is a PDF that is a photograph or a scan of a printed page, which genuinely is unreadable to software. Do not scan your CV. Otherwise, send the PDF.
The rules that depend, and on what
Some advice is neither true nor false. It has a missing condition attached, and the condition is the useful part.
Photos. A regional convention, not a quality question. In the UK, US, Ireland, Canada and Australia the norm is no photo, partly because of discrimination concerns, and including one can read as unfamiliarity with local practice. In much of continental Europe a photo is standard and its absence is what looks odd. Neither is a rule about CVs. Both are rules about where you are applying. Match the market, not the internet.
Skills sections. Useful when the skill is a real, checkable thing: a language, a framework, a certification, a piece of software. Close to worthless when it is a list of adjectives. “Team player, detail oriented, self motivated” is three lines that every competing CV also claims, which makes them three lines carrying no information.
Cover letters. Worth the effort when the person reading is the person hiring, and much less so when an application arrives through a form into a queue of hundreds. Small company, named hiring manager, unusual career path: write it. Large employer, online form, no name anywhere on the posting: put that time into the CV instead.
Length beyond two pages. Normal in academia, research, medicine and some senior technical fields, where publication and project lists are the substance. Unusual almost everywhere else. If you are unsure which you are in, you are in the second one.
How to tell the difference yourself
The test that sorts almost all of these: does this rule change what a reader can find out about me, or does it only change how the page looks to someone checking it against a rule?
Findability, accuracy, relevance to this specific posting, all real. They change what the reader learns. Page count, fonts, the presence of a line about references, all cosmetic. They change nothing about what the reader learns, which is why they are not what decides anything.
The second test is simpler and slightly uncomfortable: who benefits from you believing this? A surprising amount of CV advice exists to make a product necessary. Rules about fonts, templates and formatting compliance tend to come from people selling fonts, templates and formatting compliance. We build a CV tool, so apply that test here too. The five real rules above are things you can do in a plain document, with no software at all.
That is the honest version. Most of what you have been told about CVs is about the object. Almost none of it is about the reader, and the reader is the only part of this that decides anything.