Do you track any analytical data of your product’s user documents? This data can give you some important insight about your users. To reiterate, the need to visit a user doc, is a design issue. Something is not quite obvious. An average user won’t like to complete reading the documentation before starting with product. (I agree – this could be different if your product has to deal with something very complex, such as a programming language.)

As a best practice, find the average page views of your docs.
Monitor it periodically. See if there is a spike in page views. If there is, analyse further.

See if the spike is associated with an event – For example, an important announcement or a product release. Analyse from where the traffic comes from. Is it from the product itself or through a web search? If it’s from the product itself, the corresponding product page, from where the user selected the Help menu has an issue – mostly it’s associated with a bug in the specific release.

Analyse, if at all the traffic comes from a different page that’s wrongly linked.

Try to have a Like button or a Comment option in the user document. These will help you to track user sentiments; in other words, effectiveness of the document.