Private blog networks (PBNs) are considered unethical and are generally frowned upon by search engines. Therefore, it's not advisable to use a PBN, regardless of the number of links. If you are concerned about improving your search engine rankings, there are many other legitimate and effective ways to do so, such as creating high-quality content, building backlinks from reputable websites, and optimizing your website for keywords and user experience. These tactics may take longer to produce results, but they are more sustainable and will not put your website at risk of being penalized by search engines.