In the sentence,
The company experienced strong year[-]over[-]year growth., how does the Chicago Manual of Style govern the hyphenation?
Part of me believes that it falls under the "phrases, adjectival" rules in § 7.89.2, but I'm not entirely sure. If it is governed by § 7.89.2 "phrases, adjectival" then my understanding is it would need to be hyphenated if preceding the noun like the example.
When compound mod fiers (also called phrasal adjectives) such as high-profile or book-length precede a noun, hyphenation usually lends clarity. With the exception of proper nouns (such as United States) and compounds formed by an adverb ending in ly plus an adjective (see 7.86), it is never incorrect to hyphenate adjectival compounds before a noun.Seems like you are right! I suppose this is a a "compound modifier phrasal adjective?