PS: As I was proofreading the post, I realized I wrote "I am not basing my observation on any hard rule that I know of, just how it sounds" and added another "on" to make it "I am not basing my observation on any hard rule that I know of, just on how it sounds." I then saw that I was in fact applying the same rule discussed in the post!
Yes. I suppose that's one of the differences between Arabic and English.
Here is an instance of repeating a word after a conjunction,
Here the repetition of the word أماني was necessary. Leaving it out would have caused an undesired semantic/syntactic ambiguity; the difference between بأماني أهل الكتاب (by the wishes of the people of the Book) and بأهل الكتاب (with the people of the Book)!
And here's another example of not repeating the preposition,
Here, repeating the preposition is not only unnecessary, it would've made the sentence hard to pronounce!
And here's an example of not repeating the preposition, though repeating it would've been equally eloquent,
And finally, here is an example of repeating the preposition,
My impression of which is that it is for emphasis.