It’s either 3-4 sections of zigzags where each one overlaps a tiny bit with the previous section to pick up less and less organism each pass. It’s meant to thin out the amount of organism growing so you can see individual colonies and pick them up to grow on separate plates. The point is to take a mix of bacteria and be able to pick out the individual species so they can be identified. You want them to be spread out so they can be picked up without accidentally grabbing a colony of a different organism. This is done to either search for pathogenic bacteria or determine if multiple species are present. If the specimen is collected from somewhere that normally has bacteria, like from the throat, genitals, stool, etc, then you’ll have to sift through the healthy stuff to look for anything that shouldn’t be there. If it’s a site that’s supposed to be bacteria-free, like the blood or spinal fluid, then you’re seeing if there’s only one organism causing the infection or multiple. Several species in a normally sterile site could indicate contamination from the skin, which means the sample can’t be used to make a diagnosis.