It’s amazing that Watson, the IBM computer, can diagnosis cancer, but it can not tell you where to place a comma in an English sentence.
Of course you can’t get two different English grammar teachers to agree where to put a comma (in all cases). Those teacher will give you an F if you don’t follow their personal rules (and you have to declare them gods of the English language).
Take the simple case of putting commas between two or more items in a row. There’s Harvard way where you put a comma after each item, including after the item just before the conjunction (usually an and). Then there is the other way where you don’t put a comma after the item before the conjunction, expounded by that other Ivy League college.
If you write articles for magazines you should be using the AP style guide and not put a comma before the conjunction, unless the editor or publisher went to Harvard.
If you write books then you should use the Chicago Manual of Style which requires you to put a comma after the item before the conjunction, unless the editor or publisher went to that other college.
One author was talking about finding editors and she required the editor to use the Chicago Manual of Style. She sent prospective editors a sample of her writing. In that sample she had two places where there were items in a row. If the editor did not put a comma after the item before the conjunction then she knew the editor did not know the Chicago Manual of Style. For the editors that put a comma before the conjunction in one place and not the other she knew that they were bad editors.
Revenge. Last month I attended the Condor science fiction convention. On one panel of science fiction book authors was a teacher of High School English. She had a YA book at a publisher. The book publisher removed all the commas form an action scene to make the scene read faster. She was indignant, she knew where comas belonged, she was a teacher. She left them out. She wanted the book published.
We need more publishers like that.
Stay strong, write on. Professor Hyram Voltage