Effective project structure is crucial for developing maintainable and reusable code in Go. A well-organized codebase enhances clarity and allows for easier sharing of packages. The lesson emphasizes the importance of separating functionality into packages, such as creating dedicated `counter` and `display` directories, to avoid cluttering the main package. This modular approach not only facilitates code reuse across different projects but also supports better testing practices by utilizing public interfaces. Additionally, it highlights common practices, such as employing a `cmd` directory for the main application logic, which simplifies imports and improves the developer experience. Ultimately, understanding the flexibility in structuring code empowers developers to tailor their approach to fit their specific needs while maintaining good practices for future collaboration and scalability.