Let me unpack that a little. If she told you to spell accommodation with two cs and two ms she was right. But if she drummed into you that commas were essential in lists of items, the rules have changed. If you’re shopping for peas, beans and squash, the Oxford comma, which used to be placed after the second last item and before the ‘and’, is now a thing of the past. Don’t add one there. If the list is confusing without one—say you needed to buy peas, macaroni and cheese—rearrange the list. Buy macaroni, peas and cheese.
Languages are living entities, frequently changing. New words come into use, old ones become obsolete. Authors keen to make a good impression on editors and agents, make sure they keep up with the changes.
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