Frequently updated websites are favored by all the major search engines. Especially Google. While freshness of content is far from the only contributing factor, it goes a long way to signaling, not only to search engines, but to your customers that you care about the quality of information you are puting out. Outdated data and information could lead to overall confusion and users becoming disinterested in, not only your site, but your brand as a whole.
Another reason why website maintenance may be crucial to your site, is if the information your are providing changes frequently. One prime example of this is e-commerce. Product data is one of the more ever-changing pieces of content that exists on the internet. Keeping current and potential customers updated on these changes is an absolute must for any business who wants to have longevity in this field.
As a general rule of thumb, the more content and site data you have, the more it becomes necessary to manage it. Small changes can consume large amounts of time if the proper maintenance is not kept up.”