The keyword density for SEO means how many times the targeted keyword has appeared on the page being search engine optimized. The density of the keyword helps search engines to determine the content topics.

Good keyword density depends on the length of content on-page. For an article or post, 3 to 4 percent of keyword density would be fine.

Keyword density should be moderate i-e 1% to 2%. Having too high keyword density may hurt SEO. Having too low keyword density may or may not affect SEO. 

For example, In an article of 1000 words, having a targeted keyword repeated for 30+ times would possibly represent content spam.

If you need to use keywords multiple times to ensure contextual correctness and clarity for algorithms and users then, try with secondary keywords and LSI keywords in the content for SEO.