A good React component has a clear responsibility. It should be easy to understand, simple to reuse, and predictable when its data changes. When components try to manage unrelated concerns, small updates become harder and visual consistency starts to drift.
Reusable components work best when their structure and content are separated thoughtfully. Shared buttons, cards, navigation elements, and form controls can keep an interface consistent while still allowing each page to communicate its own purpose.
Maintainability also depends on naming, sensible data flow, and testing at different screen sizes. The goal is not to create the smallest possible component; it is to create components that help the next change feel safe.
When a component is reused, its content should be supplied as data rather than copied markup. That makes it easier to fix a spacing issue once, update a label consistently, or add another item without introducing a new variation by accident.
The most valuable React code is not the code with the most abstraction. It is the code that makes the interface easier to extend while keeping the behavior obvious to the person who will maintain it next.
Before extracting a component, look for a real repeated pattern or a clear responsibility. This keeps the component tree practical and avoids creating layers that make a simple page harder to follow.