It's probably used considerably more in spoken English, where intonation can help with the ambiguity. I have a hard time believing somebody would use "had" so m

It's probably used considerably more in spoken English, where intonation can help with the ambiguity. I have a hard time believing somebody would use "had" so many times together in writing without trying to rephrase themselves. 'Have' is also an interesting case, because aside from meaning the act of possessing, it is also a kind of case/tense modifier for other verbs. ("I ate" vs. "I would have eaten" + "the whole tub of gelato.") In the writing above, you put the third had in single quotes, which implies you're discussing the word usage itself rather than trying to use it again. Similarly, your intonation would probably be elongated. Granted, a non-fluent speaker may not yet pick up on these cues, but they are there.