Many recipes use parchment paper. I do not have a rule for when I use parchment paper. Some brands have sheets of parchment paper designed to fit in a baking pan. I have a roll of parchment paper. I also have a roll of wax paper. Paper from a roll does not stay flat on the bottom of a pan. There are some pictures below that show how I overcome this problem.
A person does not always have to clip when cutting paper with scissors. Once the scissors have started cutting the paper, someone can push the scissors in the open position to cut the paper without clipping the paper. I do not have enough hands to give people a demonstration. I used to watch people cut wrapping paper using this method when I was young. I believe that cutting a straight line is easier when the scissors are pushed through the paper.