One, two, and three? Or one, two and three?

Question

I was taught that you put one less comma than there are words or nouns. Kind of like cutting bread. (3 cute=4 slices). But then a lot of people, even authors and writers, combine the last two things. But I got to thinking, and if you combine the last two things it would make it just one compound noun. For example, if you said that Sally plays softball, basketball and softball, basketball and softball would technically be one sport. And I did some research awhile ago asking which is write and which is wrong. My results were the no comma thing was used for newspapers to save print.

Answer 1

I was taught that either way is correct, but be consistent.  Pick one way and stick to it throughout whatever you're writing.