Google’s John Mueller said that removing internal duplicate content and other technical issue fixes won’t lead to your site recovering from a Google spam update. John said that these spam updates look more at the “actual content” than if you have technical issues or duplicate content on your site.
John said this before, saying that you cannot fix your overall website quality by making some technical changes. He also described that technical issues generally lead to a slow decline, whereas algorithmic changes on Google’s end lead to a quick decline.
John later added, “In practice, going from something that’s seen as spam to something that’s celebrated takes a lot more than removing some duplicate content & rewriting a few pages.”
Everyone looks for a quick fix after their sites get hit by an algorithmic update but by then, it is normally too late for any quick fix.