In this regard, Google Developers notes on the useful content update: “How long it takes for a site to perform better if it removes non-useful content depends on how long it takes for sites identified by the system to find the signal applied to them. Our classifier works continuously and may take several months to receive signals about newly launched edits. If it is determined that unhelpful content is not signaling back in the long term, the classification will no longer be valid.”
In the correspondence, a user named Daniel Hart asked whether it is necessary to wait for the next update or whether the period works on a monthly or bimonthly basis, and the response was that our classifiers are always working.