The geometry of lawnmowing

There is a certain way you are supposed to mow lawns. You go around in a square, slowly mowing inward into a smaller square. However, mowing the lawn here at the cottage this morning, I can't help but wonder who thought this approach up? A cottage lawn, certainly, is never square. I ended up mowing shapes that looked to have been designed in AutoCAD by a half dozen engineers. They certainly weren't square. :-)