We surveyed our Twitter followers to find out which test they wanted us to run next. Most of them were wrong! However, before we delve into the reasons for the incorrect result, let's see what SEO professionals have to say about it. For the types of searches that this page is likely to rank for, I think it will improve. However, adding a specific year and month to some pages with broader intent could be negative. A travel website hypothesized that adding the current month and year to the page titles of their detail pages would allow them to stand out more from the other search results and improve organic traffic. They used SplitSignal to make the page title change for 900 detail pages, chosen as either control or variant. The model predicts what would have happened if no intervention had been made. The change made the result more noticeable, but users didn't click on it more often than predicted. It seems that the decrease in clicks is only due to the way Google users behave. Testing allows you to quickly implement changes that have been proven to be positive.
(source: https://www.semrush.com/blog/seo-split-test-result-adding-month-and-year-to-page-title)