How to nail focus with Peak Highlight on FujiFilm X-Series cameras?

FujiFilm X-Series cameras offer Focus Peak Highlight assist mode. However, the manual provides inadequate usage instruction, stating:

Focus Peak Highlight: Highlights high-contrast outlines. Rotate the focus ring until the subject is highlighted.

In addition to color, there are two settings in the menu: Low and High.

How can I use focus peak highlight to get sharp, in-focus images? How do I decide which settings (Low/High/Color) are best to use?

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  This question is not about using the menu to change the settings.

  
  


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  I expect use of this focus assist mode to be similar across X-Series cameras. If not, I am primarily interested in the X-T20 and X-H1. Secondarily interested in X-E2/S. Not interested in X-T3/T30.

  
  

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