It depends on which of two jobs you mean. Writing your first complete CV from nothing takes a long sitting, and most of that time goes on remembering and checking facts rather than writing sentences. Adapting that CV for a specific job should take a fraction of the time, and it is the part that decides whether anyone reads past the top.
Two jobs with one name
When people ask how long a CV should take, they are usually asking about the first one: sitting down with a blank page and producing the whole document. That is a real piece of work, and it is slow for a reason that has little to do with writing.
The second job gets far less attention. Every time you apply for something, the CV you send should be the version of your history that fits that role. Most people treat the first job as the work and the second as optional. From the hiring side it looks the other way round.
Why the first version is slow
The slow part of a first CV is not the prose. It is recovering the raw material: dates you have to look up, job titles that changed halfway through a role, what a project actually delivered, which tools you used and where. Much of it lives in old emails, old contracts and other people’s memories.
That is also why the first version tends to come out weaker than it should. By the time the facts are assembled, the energy to make them specific is gone, and the bullets settle into duties (“responsible for…”) instead of what changed because you were there.
A first CV rarely stalls on wording. It stalls on one missing fact: a start date nobody wrote down, or a result that was never measured. Mark it, move on, and come back to it, rather than letting one gap hold up the whole document.
A practical way through it: collect first, write second. Put every role, date, result and skill into one rough document without worrying about length or wording. Only then start cutting it into a CV. Trying to do both at once is what turns a long evening into a lost weekend.
Why the adapted version should be quick, and is still worth doing
Once the complete history exists, adapting it for a job is mostly selection and order. Which roles lead, which results sit at the top of each role, which skills the posting actually asks for and whether they are visible in the first screen of the document.
This is the step that matters most to the person reading. A screener working through a pile is matching each CV against one role, quickly. What they see first is decided by the order you chose, and a CV sent unchanged to every posting puts the same things first every time, whatever the role asks for.
An unadapted CV is usually easy to recognise from the other side of the desk. The first third of the page is about a different job: the things this posting leads with sit near the bottom, or appear once in a list, while the space at the top goes to whatever mattered for the last application.
What adapting is not: rewriting your history to match the advert. A role you did not do does not become relevant because the posting mentions it, and a skill you do not have should not appear because the job asks for it. The work is choosing and ordering what is true. Tailoring a CV to a job description goes through that line in detail.
Where the time usually goes wrong
Two patterns make CVs take far longer than they need to.
Polishing layout before content. Hours on fonts, columns and icons, on a document whose bullets still describe duties. Layout matters, but a clean single-column page is enough for almost every application, and the reading time goes on the words.
Perfecting one version and sending it everywhere. A lot of effort goes into one “final” CV, which then goes to every role unchanged. The effort was real, but it was spent on the step the reader cares about least.
A related question is how much of your history belongs on the page at all, which changes how long any version takes. How long a CV should be covers that.
The short version
Budget a proper sitting for the first complete CV and spend most of it collecting facts, not wording them. After that, each application needs a much shorter pass that reorders and trims the same true history for the role in front of you. If you only have time for one of the two, a plain CV adapted to the job will do more for you than a beautiful one sent everywhere.
JobShaped is built for the second job. You upload the CV you already have, paste the job, and it reorders and rewords what is already there for that role, working from your own history rather than the advert, so the quick pass stays quick.