Google expects pages to “be edited, reviewed, and updated on a regular basis” especially if they are for important issues like medical information, and states not all pages are held to such standards, but one can expect that Google wants information updated in a reasonable timescale. How reasonable this is, is dependant on the TOPIC and the PURPOSE of the web page RELATIVE to competing pages on the web.
Search engines may penalize sites they discover using black or grey hat methods, either by reducing their rankings or eliminating their listings from their databases altogether. Such penalties can be applied either automatically by the search engines' algorithms, or by a manual site review. One example was the February 2006 Google removal of both BMW Germany and Ricoh Germany for use of deceptive practices. Both companies, however, quickly apologized, fixed the offending pages, and were restored to Google's search engine results page.
Google knows who links to you, the “quality” of those links, and whom you link to. These – and other factors – help ultimately determine where a page on your site ranks. To make it more confusing – the page that ranks on your site might not be the page you want to rank, or even the page that determines your rankings for this term. Once Google has worked out your domain authority – sometimes it seems that the most relevant page on your site Google HAS NO ISSUE with will rank.
The ranking of your website is partly decided by on-page factors. On-page SEO factors are all those things you can influence from within your actual website. These factors include technical aspects (e.g. the quality of your code and site speed) and content-related aspects, like the structure of your website or the quality of the copy on your website. These are all crucial on-page SEO factors.