
Hi @john john,
Question-1) is my above 4 points valid and accurate? or I am missing something?
Yes, you are totally right. As a supplement, you can also share a document library or list or a site by adding the user to your existing group.
And you can also share the file via this "Share" option.
Question-2) when to use each option ? and is there a method that is preferred over the other?
If you want the user access the file via a shared file link and set something like expiration date and password, you can choose option-1. It's good for temporary access scenario;
If the user has been added to your organization and access the file via the SharePoint file path, you can choose option-2;
If you want the user to be assigned with custom permission level (not just can edit or can read), you can choose option-3.
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