From what I was taught at school, (1) (6) and (11) should be replaced by "he", because the proper name "Masao" is already mentioned earlier, and no other person who is hard to distinguish was mentioned.
Am I correct ?
Those pronouns
could be replaced by "he", and perhaps they would in ordinary usage, but the language doesn't demand that they
must be replaced without exception. It's simply a matter of style, and it is OK to repeat a noun every so often, as long as you don't overdo it. Repeating the noun might make the meaning clearer, or it might avoid monotony or remind the reader of the person or thing being discussed.
Note that when the noun is repeated, it's always at the beginning of the sentence. To me that seems to be the most natural place to do so, at the point where a new subject might otherwise be introduced.
Of course, this only applies to third-person pronouns. For first-person or second-person pronouns, the pronoun
must be used because it's the only way to determine the speaker's relationship to the person being talked about.
And if so, why Sidney Sheldon used the proper name "Masao" at (1), (6), (11),
and the pronoun "he" at (2),(7),(9), and (12) ?
Is that Sidney Sheldon's preference?
Is there any good/marvelous effect to choose such a way, by the famous story writer?
Rhyme?
I would guess it was simply his preference. As for the effect he desired, I don't know. Perhaps adding emphasis or avoiding monotony, as I supposed. He may not even have been conscious of it himself. I don't think it was done for rhyme, though.
If you were him (Sidney Sheldon), would you decide to choose the proper noun and the pronoun just like him?
I doubt it. Perhaps I would repeat the name at some point, but my personal preferences would probably differ from his.
This was an interesting question. I don't remember ever thinking about this issue before.