If the ideal keyword density for SEO is 1-3%, it follows that a web page should run at least 100 words or so (e.g., if the word “density” appears once on a 100-word page, the search engines will judge it to have a density of 1% and just might give the entire page prominent placement in their results for a search including the word “density” [after also factoring in a gazillion other factors]).
However, that can make for a really short page (especially if it’s an article), and the most important thing to strive for is to make the page useful and readable for visitors to that page.
One other hint that brevity could be divine in the eyes of search engines is the fact that the Google home page word count is 16 as of 2019 (and this word count is down from years past).
Long story short (no pun originally intended, but it works here), it goes back to what you might’ve learned in high school, in more ways than one: writing pieces are ideally like a girl’s skirt … long enough to cover the subject, but short enough to keep it interesting …
And what about that “density” example? Well, a paste into Google Docs yields a total page word count of 258 with the appearance of “density” on the page seven times, making for a keyword density of 7/258 = 2.7% (most likely this page won’t have a lock on relevant SERPs any time soon, but only time will tell).