Generally, a literature review should aim to provide a comprehensive and up-to-date overview of the existing research and scholarly literature relevant to the research question or topic. This means that the number of studies or literatures included in a literature review will depend on factors such as the breadth and depth of the research question, the availability and relevance of existing research, and the scope of the research project.
It is important to ensure that the literature review is well-organized, critically analyzed, and clearly presented, regardless of the number of studies or literatures included. The focus should be on selecting high-quality and relevant sources, rather than simply aiming for a specific number of sources. A literature review should provide a thorough synthesis and analysis of the existing literature, and should demonstrate a clear understanding of the key debates, trends, and findings in the field.