Photo by Sean AdcockA dry stone wall doesn't have to be coursed. In fact in the case of terracing it can be a detriment. Here is one example of many of the uncoursed walls in Mallorca that are all holding back tons of earth over the hilly terrain on the western side of the island. These walls stop a lot of erosion caused by heavy rains they experience there every year. The Mallorcans would have done coursed walling if they thought it made for stronger, longer-lasting structures.