October Novel Prep Challenge

Can someone tell me if when you write dialog, do you have to say who was talking at the end of each persons speaking if you are double spacing between persons. And if you do double space and don't include who spoke each time does it have to be consistently written in that form.

Or should I just keep the dialog in the same paragraph and put who said it after each change. It just seems monotonous when I write it that way.

Thanks Jo