Question: When do we use auto-import?

The answer is, when a component of a package or a package is used in almost all files of the project.

Question: When do we not use auto-import?

When a particular component is used just once or twice in a project, we do not auto-import instead we import it in the specific file/s where the component is required.

Question: Why do we not auto-import all the components or packages?

It downloads the complete package in our project making the size of the project unnecessarily big.