A recommended best practice on the JAMstack is to trigger a new site build and deploy for every new change that comes through. This ensures that sites are kept consistent across a globally distributed set of CDN servers. As you can imagine with this setup, build times increase as sites scale. In the case of data-driven industries like e-commerce where content (that significantly drives revenue) is ever changing, time is of the essence. In order to stay competitive and relevant, updates need to be instantaneous. The JAMstack approach of atomic deploys poses a challenge to larger sites like these with over thousands of pages since builds tend to be lengthy.
A key strategy to speeding up large site builds is by building incrementally. Incremental builds is the concept of re-building only the parts of a site that changed. To accomplish this, older content that doesn't change remains cached, while modified content is regenerated and updated to the cache. This way, deployments are perceived as instant. In spite of how ostensibly simple incremental builds may seem, they are in fact a tricky business. Most notably, incremental builds require pinpointing exact changes and updating the build appropriately. Because of the complexity of incremental builds, many SSGs have yet to implement them (without charging for them) and this technique remains fairly inaccessible for now.
A more accessible way to achieving faster builds is to decouple dynamic content like price from the prebuilt markup itself. APIs like Commerce Layer allow you to inject content at request time while serverless functions enables you to leverage dynamic server side functionality at the edge as needed. The combination of static with dynamic means that you can stay confident that time sensitive content is always up to date.
For more on incremental builds with regards to SSGs, check out React Static, an SSG built for React and the only SSG that currently supports incremental builds (for free)