This is an excerpt from my English textbook
Their parents take care of everything, from A to Z, not to mention tuition and room and board. Though many students work part time after school or during vacations, the money they earn is for their own personal use---for dates, for traveling, for club activities.
My question is about styles. Is it acceptable to write "A and B and C" or "A, B, C" in a formal writing?
I am not sure if you should be formal in a textbook but then how casual is it to write this way?
What is the advantage of writing casually over formally especially in this quote?