As you write, you likely also do some reviewing. You may move sentences or paragraphs around, delete some content, and add text to some areas. The more you read through your work, the harder it can become to edit it and, frankly, the less you may feel like it.

All written work can be improved by an experienced editor, whether it’s an article, thesis, dissertation, case study, proposal, application document, résumé, CV, white paper, policy document, course material, exam, assignment, website text, terms and conditions, or a novel. What’s not to like?

Editing renders writing ready to go out into the world. It helps establish professionalism in higher learning and in workplaces.

Professional copyeditors look at your manuscript as an experienced first reader, with skills they have developed over years. We identify and fix mistakes, inconsistencies and sentences that confuse readers and that may lower their opinions of us – examiners, peers, institutions, friends, parents, prospective employers or others.

Poor attention to detail, errors and inconsistencies mark an author as unprofessional and unprepared.

Copyediting removes errors and improves a manuscript’s language, flow, tone and style. Particularly for authors who are ESL or EFL, journal editors and reviewers may find your work hard to understand, which can make for rocky interactions.

No matter how many people read a text, errors somehow sometimes slip through. Errors are frustrating. They show that the author did not care enough about the reader’s experience to follow the process needed to produce a good text: submit it to beta readers and reviewers, correct the errors, and then have it professionally edited and proofread.

The goal is simple, clear, concise, consistent and reader-focused text. It takes time, effort and resources – there are no short cuts to doing something well.

So, how many errors are acceptable in a manuscript?
Different publication types and publishing areas have different standards and requirements. A text’s nature and goals may determine the number of reviewing rounds or layers. In some traditional publishing processes, three or more sets of eyes go through a manuscript in great detail; still, they seldom catch everything.

Are errors acceptable in a text and, if yes, how many? Some say that a text that was hastily proofread by one proofreader may have one typo per 1,000 words; others say three per 10,000 words. To some, one error per page is a very high ratio.

One reason to keep the number of known errors as low as possible is that we cannot count unknown errors. The best case is: as few as possible, preferably none.

Conni Eversull: “It can be done, and it is done many times each day by careful writers. I have a copy of ‘Gone With The Wind’… that is over 500 pages long, and there is not a single error in the entire book… Our bottom-line answer… is NO, there is no acceptable number of mistakes for any published document”.

Sources
Conni Eversull (9 November 2010): Acceptable number of document errors?

Scott Bury (28 August 2017): How many typos are acceptable?