How can the oxidation of TEMPO be selective?

According to the article "[**TEMPO oxidizes alcohols to aldehydes and ketones**](https://www.liskonchem.com/TEMPO-oxidizes-alcohols-to-aldehydes-and-ketones-id3275509.html)", the oxidation of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl, 2564-83-2) can be highly selective. I assume it means you can easily choose to oxidize primary alcohol or secondary alcohol by controlling the conditions of reaction. But how to do that exactly? What conditions should be modified and how?


