How important is fresh content on inner pages

Of course, I try to find incoming links for these inner pages, this helps a lot. However, I’m not sure if it is really required to update these inner pages once in a while. I’ve heared from others that it is not important because it is natural that an article will remain the same for a long period of time. For example: the roulette rules don’t change so if you already describe every aspect in your article there is no need at all to change it..

I’m not convinced since I sometimes do see an increase in rankings after updating an inner page. What are your experiences with this? Is it important or not?

I thought about adding news headlines to the inner pages. This would mean that I would add the latest 5 news headlines (of news shown elsewhere on my site) to each article, they would change automatically since new news articles are added frequently. This would facilitate fresh content on the inner pages but it would not always be relevant. Another approach would be to view 5 headlines of random news articles, this way the inner pages would be somewhat different on each pageview. However, I’m not sure if either of these approaches would help me or if it would only hurt my rankings. Anyone who has some ideas on this?