You do not need to put any grease or oil on the parchment paper. Cookies will slide off the paper if you pick them up with a spatula and a cake will come out of the pan easily. Parchment paper can be used for several batches of the same recipe being baked on the same cookie/baking sheet in a few batches.
In this regard, do cookies take longer to bake on parchment paper?
Using parchment paper to bake cookies can save time and energy. Unbaked cookies are placed directly onto the parchment paper, eliminating the need to grease the cookie sheet. While a batch of cookies is baking, portion out the remaining cookie dough onto sheets of parchment paper.
Hereof, when should you not use parchment paper?
When Not to Use Parchment Paper
Parchment paper is not designed for high heat cooking. Avoid using it in your oven or on the grill if temperature will exceed 400 degrees, says Michelle Weaver, chef at Charleston Grill in South Carolina, as there’s a chance it could catch fire.