Depending on the size of the cookies, I bake 6 to 8 cookies in two rows on my half sheet pan (13×17 inches). I prefer parchment paper to a silicone baking mat.
I like to only bake one sheet pan of cookies at a time on a rack placed in the center of the oven. This way they bake evenly and I don’t have to remember to do any rotating. I have two sheet pans going at a time: while one is in the oven, the other sits for a few minutes before I move the cookies to a cooling rack and prep the next batch.