Sometimes, the rendering is "good enough", but you are rendering in Batch Mode and you don't dare to stop it.
To Stop Rendering This Frame and Start Rendering the Next Frame in the Batch:
- Right click the image
- choose "Stop before next pass" this will stop only this frame (give it time, as it will finish the pass in all threads on your machine).
When it has finished the pass with all threads, it will automatically save the image, and then start rendering the next frame in the batch.