Day one of wet and forget treatment.  I have done regular treatments on presidential style roofs with wet and forget with just regular maintenance of gutter cleaning and air blowing.  After a few years of regular wet and forget treatments and regular air blowing, the moss is gone and the roof is looking like new without the use of a brush or a pressure washer.  I will prove it to you.  Here is the mossy roof, and I will bring you pictures and videos of the phases and the process as it proceeds.