I have very few rectangular fields so a couple rounds and then start back and forth mode along the longest stretch. Round and round in some of my fields can end up with 2 or more small patches and numerous corners to cut out. I use the same setup in reverse when working or planting. Go back and forth then a couple times around the outside. Might add, terraces sometimes make the around and round almost impossible if you want to keep header full. | 
To Round or Square? That is the question.
