Looked at comparisons a day or three ago--maybe yesterday, maybe Wednesday, maybe Tuesday. "Recently."
Now, a lot of times you have little choice in what you say. "The definition of pH based on [H+] concentration is ..." and you're going to say the same thing a million others have said in the last decade. Like having to quote that "Washington DC is the capital of the United States." Background noise. But some of the quotes were fairly idiosyncratic and while probably not novel utterances they'd be rare, and you get 10, 15, 30 of them in a passage and you're pretty much left with "they cribbed this."
They were lazy. Or assumed nobody would notice. Unlike one professor in my dept. in the '90s who would spend days in the library verifying every reference--looking them up if local, using databases if he couldn't actually peruse the original. His students would get comments like "You cite ______ but on page 231 as you claimed your quote is not to be found. Correct it." And it would be found by the PhD candidate not on page 231 but straddling pp. 231-2.