Q. MS Word doesn’t like the “of” in this sentence: “All of these valves are on separate channels.” It puts a blue dotted line under “All of” and wants to get rid of the word “of” even though “of” starts a prepositional phrase. Is this some new trend? I know I could reword the sentence to read “These valves are all on separate channels,” but that seems to be a lot of work for what used to be (what I thought was) normal.
A. According to Bryan Garner, all the has been more common than all of the “since the beginnings of Modern English,” a pattern that holds when a word like its—or these in your example—is substituted for the. A Google Books Ngram comparing the frequency of the phrases all the things and all these things with and without of in published sources since 1800 backs this up. Substitute valves for things and the of-less versions are still in the lead. So it’s not a new trend. For whatever reason, the preposition of has long been considered optional or unnecessary in sentences like yours.
Still, as Garner notes, there are some exceptions, including when all is followed by a pronoun that isn’t either demonstrative or possessive, as in all of it (not all it). See Garner’s Modern English Usage (5th ed., Oxford, 2022), under “all. A. All (of).”
OK, but—exceptions aside—should you change all of to all “whenever possible,” as Garner suggests and Word supports? Yes, if you’re looking to cut unnecessary words, as editors usually are. But the phrase all of is just as correct as some of, many of, and most of—grammatically similar phrases that all require of where it might be optional after all.
So if you happen to think that all of works better than all in any given sentence, simply ignore the dotted blue underline, which is triggered by one of Word’s checks for “conciseness.” Most editors understand the value of being concise, but we also want things to sound natural.
Tip: In the desktop version of Word for Windows, the conciseness checks are listed in the Grammar Settings dialog box, which you’ll find by going to File > Options > Proofing, under Writing Style > Grammar & Refinements > Settings. If the box next to Wordiness (under the options for Conciseness) is checked, that’s what’s causing Word to flag all of. (Settings in Word for Mac will be similar.)