When should I delete Xcode Derived Data folder and when should I not?

I have been working in iOS project. Regarding Xcode Derived Data folder whose contents are generated by build system, there are many Stackoverflow posts, i.e. how to remove derived data folder or is it safe to remove derived data folder, etc but there is none which I am looking for. My question is to know when should I delete the derived data folder and when should I not? In other word, in which conditions this derived data becomes inconsistent and why? Are those derived data become stale after resource or configuration change of the project or anything else? I often see many issues are resolved after deleting derived data but we often do not try to know the root cause of the issues.

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^{Background of the question: In my project, I have a proof build system so that every CLs need to pass the proof build before getting merged to remote branch. So I need to know the risks to architect when I should (or should not) reuse the derived data folder to make the proof build system performant.}

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