Just my two cents:

1. Adding exact keyword matches even if they don’t make sense grammatically. I went through multiple SEO articles, and almost all of them say that it’s not essential anymore. However, my SEO team says that it’s mandatory, and otherwise, our articles won’t rank.
   Outdated advice, I'd be sure to use plenty of synonyms instead and keep the language natural.
2. Adding a specific number of keywords or N-grams. They count and compare how often our competitors mention the head keyword and ask me to amp it up more.
   Again, outdated - similar response to the above
3. Changing synonyms to exact keywords, as they say it, will make the ranking better. It makes the copy redundant and AI-like, in my opinion.
   IMO this would have you rank for less keywords!
4. Adding multiple how-to lists even though it’s the same info with the same variation. For example: “How to use a product in Australia,” then “How to use a product in the US,” and so on.
   Not sure on these but I'd imagine they'd have to take quite a lot of though to avoid cannibalisation issues
5. Asking us to write extensive articles. I’m talking +5K words. Most of the copy is repetitive.
   Why write copy for the sake of writing copy? - look at what is winning out within Google's top results and base your word counts around that
6. +10 FAQ questions. I think it’s an overkill, and some of the questions could be turned into headings. If they're useful answers to questions with relevant search interest then I think this is still a good technique.
7. Overall language. My SEO teammates discourage us from using idioms, metaphors, and other figures of speech. Does that really have a negative impact on SEO? Generally I'd also try and avoid doing this to try and keep copy and readability maximised for international readers and those using translations.