Yes and no.

Conceptually, the UI re-renders itself completely in order to always be an accurate reflection of the model.

That is the #1 job of the view: be an accurate reflection of the model.

And re-rendering itself completely is a safe way to implement that requirement.

However, the UI can also look at the model in more detail and figure out what parts need to change, as long as the effect is the same as re-rendering everything.

And the model can tell the view that specific subparts of the model have changed to make that job easier for the view.

But if it can't figure out the details, the fallback is to re-render the entire view from the model. But not to recreate the view. The view sticks around.

One way of doing this optimization is "damage rects" like Cocoa does. Another are the polymorphic identifiers used in the update queue of Blackbird.