You are hired by a retail clothing brand "Cool Fashion" as their digital marketing executive. In a meeting with your manager, she asked you to help grow the number of visitors to the brand's e-commerce website. As a digital marketing executive, you understand that 'Search Engine Optimization (SEO) is a continuous process".

Explain your understanding of this statement with examples of why SEO is a continuous process for digital marketers. Include at least one (1) example of an SEO task that would need monitoring during the launch of a new marketing campaign, along with identifying one appropriate metric to evaluate the SEO effectiveness of the launch.