I just completed an article for a magazine. The original version was about 1400* words long, so the editors removed the last couple of paragraphs, made other minor modifications, and returned the article to me. I accepted most of their edits, added back the “missing” paragraphs, and sent them a note explaining their version was missing text, so I'd added it back. The editor replied explaining the article was too long, so they'd removed a block at the end.
I read their email several times, finally deciding it was worth a laugh. These folks had never heard of the 1/3 rule. I heard if first from Jerry Weinberg (the whole exercise is in Weinberg on Writing).
For a 1400-word article, I didn't need to cut 1/3 of the pages or 1/3 of the paragraphs; I just needed to could cut 1/3 of the words. And, without much trouble, that's what I did. The article is much tighter, reads more clearly is clearer, and feels “lighter” to me. When I do my 1/3 exercise, it feels a bit like refactoring.
(I tried to show you what I do with the above paragraph. I cut 15 out of 64 words, not quite 1/3, but close. I hope the strikes help you see how I think about cutting words. I excise adverbs and then reconsider adjectives. Then I look for compound verbs or nouns to see if I can replace them with a better–stronger–word.)
Now all I have to do is explain this to my editors, so they don't just excise. Pruning by 1/3 works, and works on every level.
* I'd originally written 200 here, not 1400. Bet this makes more sense now. Thank you, George, for letting me know.