If, for example, in the title tag and H1 tag of your home page you used the keyword phrase "Texas hill country land for sale," and assume this phrase was rarely used in Google searches. But segments within that phrase "Texas hill country" and "land for sale" were highly used and recommended for optimization. Would the fact that the entire phrase "Texas hill country land for sale" was rarely used negatively impact the two highly used phrases within that phrase Texas hill country" and "land for sale"?
Actually, I don't think it'll affect your campaign negatively. However, I do know that Google may get confused and crawl "land for sale" or "Texas hill country" instead of the long-tailed version. If you're doing local SEO or for a website with little or no competition, then "Texas hill country land for sale" should be prioritized for now. I'm pretty sure the website's rankings for that particular keyboard would skyrocket given that there may be no other website optimizing that keyword.
It's not a very good idea to use more than once the H1 tag. It should contain ONLY the main keyword and if you want to create different keywords, go with H2 or b tags!