Welcome to the world of weaving with individual shafts! Most of the time you are weaving with 1 thread as your weft pick - the thickness of the pick in any particular project is decided by the thickness of the yarn. Have you gone back and watched Season 1 through and through? That will give you a solid understanding of the process ;-) Someday, further down the road, you will learn that sometimes there are exceptions when you explore different structures that are possible on a shaft loom. In the meantime - enjoy the amazing world that you can create on "just 4 shafts", Christine!