Once upon a time, I was a brand-new copy editor brimming with enthusiasm for my newly acquired editing knowledge.
Like a lot of brand-new copy editors, I didn't have much context for understanding the rules. I didn't realize that most were style conventions and not true grammar rules.
So I applied those style conventions with a passion reminiscent of guards in the Stanford Prison Experiment.
I've since learned that some editing rules shouldn't be taken too seriously. And I'm always amused when I see a piece of writing edited with the same eager-beaver naivete.
Here are some of editing rules I and other editors have taken a bit too seriously.
"Such as." There's a longstanding belief, enshrined in some editing styles, that "like" can't mean "such as." You could argue that this is a good guideline either way, since "like" has multiple meanings and can therefore be a little ambiguous.
But sometimes this "rule" hurts a piece of writing. "In-demand travel destinations such as Hawaii and the Caribbean attract visitors from far-flung corners of the globe such as Europe and Asia."
This sentence is already wordy and a little contorted. Replacing those two instances of "such as" with "like" would smooth it out.
"Since." A lot of editors believe you can't use "since" to mean "because." Actually, this is a pretty good policy. If you're not careful, "since" can be misleading.
"Since you went to college, you learned a lot about human nature." Does this mean that you learned about human nature because you attended college? Or does it mean that you accumulated this wisdom in the years since?
"Because" doesn't leave any doubt about it. "Since" does. But overeager copy editors can take this too far, prohibiting "since" in instances where its meaning is unequivocal.
"More than" and "less than" for "over" and "under." Consider this overwrought sentence: "The class is for children more than 2 years old but less than 10 years old." The best fix would be an overhaul: "children ages 2 to 9." Short of that, changing "more than" to "over" and "less than" to "under" is the next-best thing. But lots of new editors are taught that "over" and "under" refer only to physical proximity, like the roof "over" your head. If that were true, you'd never have the option of using "over" for "more than." Luckily, it's not true.
Commas between noncoordinate adjectives. This is one of the most common eager-beaver editing errors I see: "the spacious, 800-square-foot suites"; "the beautiful, winter sky"; "the prestigious, medical school." Editors learn early that commas go between adjectives, but many miss the part about how commas don't go between all adjectives. The real rule is that commas separate coordinate adjectives -- ones that could instead be separated by the word "and." In our first example, the "spacious" and "800-square-foot" sound weird with "and" between them. That's your clue that "the spacious 800-square-foot suites" should not take a comma.
Speaking of compound adjectives, I know of at least one novice copy editor who was a little too excited to learn that these terms are hyphenated -- so excited that I, I mean she, glossed right over the disclaimer: Compounds are hyphenated when doing so aids comprehension. The rest of the time, no need. When you combine "800" and "square" and "foot" to create an adjective describing a noun like "suites," hyphens help the reader understand that those three terms are pointing to a noun yet to come. A better example: "The horror movie was about a kid-eating lobster." Without the hyphen, that's not a very good movie. But there's no need to go nuts hyphenating compound adjectives. A "sports equipment purchase," for example, works just fine without a hyphen.