Cover letters attract more confident bad advice than any other part of a job application. Some of it was true in 2012, some comes from people who have never sat on a hiring panel, and most of it survives because it is comforting. Here are seven beliefs worth retiring, what each one gets right, and what actually happens on the other side of the inbox.
Myth 1: Nobody reads them
There is a real kernel here. Plenty of letters are never opened, especially for high-volume roles where a recruiter is clearing three hundred applications against a screening checklist. If your mental model is "recruiter reads the letter, then decides", that model is wrong and has been for years.
What actually happens is that the letter gets read later, and usually by someone else. Screening runs on the CV. Then a hiring manager receives five or six profiles that all look plausible on paper and has to decide who gets a calendar slot. That is when the letter gets opened, and at that point there is very little else left to compare.
Write for the second reader instead of the first. Put the single fact that makes you the obvious pick in the opening two lines, because the person reading at shortlist stage is skimming for a reason to say yes.
Myth 2: One strong letter can be reused with the company name swapped
Reuse itself is not the sin. Anyone applying to twenty roles reuses something, and pretending otherwise is theatre. Your structure, your opening move, the way you frame a track record: all of that travels perfectly well.
The trouble is that the travelling parts are precisely the parts carrying no information. "I am drawn to your mission and your culture of innovation" reads the same whether it landed at a freight forwarder or a dental group, and the reader has seen that sentence four hundred times. When nothing in the letter required reading the job posting, the letter has said nothing.
Keep the skeleton and rewrite the middle. One paragraph tying a specific detail from the posting to a specific thing you have shipped outweighs three paragraphs of enthusiasm. If you cannot find that detail in ten minutes, you probably do not want the job much.
Myth 3: It must be a page of formal prose that opens with Dear Sir or Madam
Register does matter, and the myth defends something worth defending. A letter written like a text message signals that you did not take the process seriously, and readers do notice.
The rest is inherited from an era of paper and postage. Nobody in a hiring loop is scoring your salutation. A named greeting beats a formula, and if the name is genuinely unfindable, "Hello hiring team" is safer than a phrase that suggests you never looked. Short paragraphs, plain verbs, and even a couple of bullets for hard evidence read better than a solid block of prose, because your reader is on a phone between meetings.
Concrete rewrite: replace "I am writing to express my keen interest in the aforementioned position" with the reason you fit, stated as a fact. "I spent the last two years running the exact migration you describe in the second bullet of this posting" does more work than a whole paragraph of polite framing.
Myth 4: It should summarise your CV
This is the most common way a decent letter turns into a wasted one. The reader already has your CV, often open in the next tab. Retelling it in paragraph form hands them a slower version of a document they can scan in fifteen seconds.
The letter is the only free-form space in the whole application. Spend it on what a structured document cannot express: why you are moving from one sector to another, what happened during the eighteen-month gap, why you are applying below your last title, what you concluded from the project that failed. A tool like Postulit can turn your LinkedIn profile into a clean chronological CV in a couple of minutes, which is exactly why the letter should carry the judgement and context that no chronology holds.
Practical test: if a sentence in your letter also appears in substance on your CV, delete it and see whether anything is lost.
Myth 5: Longer proves more effort
Effort and length correlate in school. In hiring they come apart, because the reader has a fixed and small time budget per candidate, and length spends that budget on your behalf without asking.
Two hundred to three hundred words is enough for one claim, one piece of evidence, and one reason you are here. Past that you are mostly restating. A long letter also carries a risk its author never sees: it reads as someone arguing themselves into a fit rather than simply stating one.
Do this instead. Write the letter at whatever length comes naturally, then delete every sentence that would still be true if you were applying somewhere else. What survives is the letter.
Myth 6: If the field is optional, you should skip it
This is the myth that costs candidates the most, and the place where I watch sharp people make the wrong call over and over. "Optional" is a statement about the form, not about the reader. It usually means the field is not required to submit and not scored by the applicant tracking system. It does not mean the hiring manager ignores the box when someone fills it.
The asymmetry is brutal. Attach nothing and you are compared on your CV alone against people who attached something. When the pool is tight, the candidate who wrote 150 useful words is the one who looks like they wanted this specific job rather than forty jobs.
Optional fields are where a shortlist quietly gets decided.
Rule of thumb: if the field exists, put something in it, even three sentences. The exception is an employer that explicitly says it does not accept or read letters. That happens, and it should be respected.
Myth 7: AI-written letters are automatically rejected
Some companies do publish a policy, and a few claim to run detection tools. The belief is not invented from nothing.
But detection of generated text is unreliable enough that no serious process rests a rejection on it, and no reader can distinguish a well-edited model draft from a well-edited human one. What does get punished, every time, is genericness. Generic is exactly what unedited model output looks like: fluent, warm, evidence-free, and valid for any employer on earth. The tell is the emptiness, not the tooling.
Use the model for the structural work and keep control of the content. Feed it your real numbers, the real posting, and your real reason for applying, then cut any sentence you would not happily defend in the interview.
What to do with all this
The honest verdict is narrower than either camp claims. A cover letter rarely wins the job on its own, and anyone promising otherwise is selling something. What it does reliably is break ties, and a large share of hires are settled at exactly that stage.
Take one action this week. Open the last role you applied to where the letter field was optional and you left it empty, and write the 150 words you skipped. Lead with the fact that makes you the obvious choice, add one number, name one thing specific to that employer, then stop. Reuse that shape afterwards, not that text.