Best practice for translations (DocType vs lang.csv)

I would like to know the best practice for translation.

Let’s say we have an app and we would like to add translation to it.
We could add translation via the DocType “Translation” where one can manage multiple translations for multiple languages OR we add a custom lang.csv to the translations folder of the custom app.

What is the better approach? Are there any advantages/disadvantages of using either one of them?

I think that for a custom app you should use the lang.csv because the doctype translation is for the users and to send the translations to .