According to the Midjourney team, you should experiment with the combination of style and prompt. The style alone may not always transfer as intended to other prompts.

Here's their exact words:

The Style Tuner you create uses your initial prompt to create sample images and help you visualize the impact of your choices. However, the generated codes can be used with any prompt. Remember that styles and prompts always work together to generate an image, so a style code may not transfer as intended to other prompts.