There are lots of examples of this rule, as you might expect. One concerns gym membership. Eighty percent (or thereabouts) of gym members attend only twenty percent of the time available. The other twenty percent of members attend eighty percent of the time (and reap the benefits). Note that both sets of people have the same initial motivation: to get fit and healthy. But only a minority follows through by attending regularly. And normally only this minority achieves a positive outcome.
The same thing applies to submitting CVs. Everyone submits a CV in anticipation of a positive outcome –an invitation to interview. But only a minority follows through with a thorough proof reading for spelling errors, incorrect grammar, out of date timelines, and fuzzy presentation.
A badly prepared CV irritates recruiters and increases the likelihood of its ending up in the “reject” pile. A well constructed one is much more likely to end up in the “call for interview” pile. Just like the 80/20 rule, only a minority will reap the benefit of an invitation to interview. That’s the 80/20 rule of CV preparation