Shell programming or scripting should not be used for complex software development tasks or applications that require high performance, extensive graphical interfaces, or intricate data manipulation. It is not suitable for projects demanding real-time processing, complex mathematical calculations, or sophisticated user interactions. Additionally, shell scripts may not be the best choice for large-scale applications with intricate architecture. In such cases, programming languages like Python, Java, C++, or specialized tools and frameworks are more appropriate for achieving better performance, maintainability, and scalability.