I've been doing a lot of transcription lately and can't find the answer to this question to save my life. I'm sure the problem is in the way I'm asking the question.
An example of this would be, "I ran and ran and ran" or "We skated and biked and laughed." I am relatively certain that if the conjunctions are separated by actual sentences, i.e. "We skated, and we biked, and we laughed," that a comma should indeed be used. However, my editor adds commas to the former examples, and I can't help thinking she's incorrect.