Il a ses doigts sur la table.
I learned that you should avoid using possessive pronouns to refer to body parts if the subject is clear in the context. In this case, both meet the criteria, I think.
But the comments there suggest that it is better to use ses, not les. For example:
the two sentences are correct. And I prefer the duo's
I am French and How I said, two sentences are correct, but I found the duo's a little more natural.
Why is the use of ses more natural than les in this case, and how do I know which one to use to refer to body parts?