The decision to use a Builder widget versus extracting a widget into a separate method with its own build method depends on the specific use case and context of the widget being created.
A Builder widget is typically used when a widget needs access to a BuildContext that is different from the current context. For example, if a widget needs to access the BuildContext of a parent widget in order to retrieve data or perform some other action, a Builder widget can be used to create a new BuildContext that is a descendant of the parent widget's BuildContext. This can help to reduce unnecessary widget rebuilds and improve performance.
On the other hand, if a widget is used frequently throughout the app and has a complex UI or functionality, it may be beneficial to extract it into a separate widget with its own build method. This can help to keep the code organized and modular, and can make it easier to update or modify the widget in the future.
In general, the decision to use a Builder widget versus extracting a widget into a separate method with its own build method should be based on the specific requirements and constraints of the app being developed, as well as the personal preferences and coding style of the developer.