Good editors develop a memory bank of common writing mistakes.
They know, for example, that the word only is usually misplaced, causing it to become a rogue modifier in its dual role as an adjective and adverb.
They know writers often use anxious when the really mean eager, and convince when they need persuade.
When those words show up in copy, the editor's mental microprocessor instantaneously checks their usage and orders any necessary revisions.
Mose wonders about the programming of writers' and editors' brains when they read this sentence:
It was under Bush, as well, that a myriad of financial regulations were added. ...
How is your brain programmed to react to myriad?
The AP Stylebook explains that myriad is an adjective: “Note word is not followed by of: The myriad books in the library.”
But the dictionary people at merriam-webster.com don't agree:
“Recent criticism of the use of myriad as a noun, both in the plural form myriads and in the phrase a myriad of, seems to reflect a mistaken belief that the word was originally and is still properly only an adjective. As the entries here show, however, the noun is in fact the older form, dating to the 16th century. The noun myriad has appeared in the works of such writers as Milton (plural myriads) and Thoreau (a myriad of), and it continues to occur frequently in reputable English. There is no reason to avoid it.”
Dictionaries are infamous for legitimizing popular usage at the expense of tradition in grammar. Building a case with examples from Milton and Thoreau offers some history, but that does not preclude the possibility that Milton and Thoreau got it wrong.
Of course, a stylebook is a statement of preference, usually intended to ensure consistency in usage. That doesn't guarantee grammatical certainty.
Few words can smoothly perform the work of both a noun and an adjective, though that doesn't stop some writers from forcing the issue.
If you have an established style, follow it for consistency's sake.
If you have no such style, think about establishing one. Consistency can help avoid confusion.
Then think about loading it into that memory bank.