You usually get BOGO for half price in my experience.

Not necessarily. In my area, most stores actually require that you get two. Publix is the exception.

Only one or two stores on grocery day, but I saw her cut a bill in half with coupons.

I used to work in a grocery store (not Publix). I once saw someone use so many coupons that the store owed her money. I have never seen that happen since. It blew my mind at the time that that even happened. It still kinda does.