Google’s John Mueller says it may take months for major site changes to be processed by search ranking algorithms. So, if site changes were implemented around the same time as a known Google algorithm update, any gains/losses in traffic are not necessarily a result of the recent site changes. This topic came up during a recent Google Webmaster Central office-hours hangout where two site owners brought up similar concerns.
When content becomes outdated, sometimes site owners remove the old page and replace it with a new one. And they don’t always remember to use a redirect when doing so. The question came up on Twitter about whether it is best to replace the content or redirect from the old page to the new one. John Mueller from Google answered it on Twitter and said the best solution is to simply replace the content and keep the same URL.