The VOLUME of this content must EXPAND on a weekly basis and should be updated over the years. Make sure to have at least 800 words (per post or new page) with the aim of becoming an authority on the given topic and/or keywords that you are aiming to rank for. NOTE: This is not a “rule for all situations.” Rather, it is the standard way to rank well and HOLD your ranking over time. There are some cases where what is needed is NOT so much to expand your work but rather to UPDATE and IMPROVE your existing work. Examples include GOING BACK to a page and correcting typos, adding good PDF Google Scholar sourced links that validate what you are saying, and any other tweak that is useful for the overall quality of your content.
Remember that LINKS were first viewed by search engines as a means to RECOMMEND and/or VOTE for content. And (in my view) if you include high quality outbound links from your new and original content you are saying to search engines: “Yes, I am aware of what came before and my work is researched well … To be a CONTINUATION of high quality information”. Links hence must, in my view, be either PDF files or DEEP within an external site to a given page or even to the anchor tag on a given page. (Jumping down to the content).
Being an “authority” implies that whatever you say and post online may itself be researched by others and in turn be linked to by others. This in and of itself will boost your ranking if the quality of the external page is high.
Being an “authority” also implies that after a certain amount of time (generally a year) you must start the research over again and see what is NEW online. Then add external links and UPDATE your own content.