Avoid duplication of effort
In the current context, it is more important than ever to avoid unnecessary duplication of effort. Duplication represents research waste. You can address this by seeking to identify existing published evidence syntheses and those in preparation.
Where current, credible and comprehensive reviews exist, these may be sufficient to address the question that you were proposing to research. In some cases, as the interactive flow diagram demonstrates, the reviews will not be current. In such cases an update may represent a more useful and efficient contribution to the research literature than a review that starts from scratch.
Sometimes, having accessed and assessed existing evidence and those in preparation, researchers may decide that for a variety of reasons the review should be replicated. This may relate to the formulation of the question, the context, or uncertainties around the credibility of conduct or reporting. Conscious replication of reviews in such instances is fully justifiable.