I've only done a couple.
I mix in a 5 gal bucket: two gallons of chlorine, cup of soap, & 1-2 ounces of TSP, fill rest of bucket with water.
Spay on roof, let set for 15-20 minutes and go to town. I spot spay the heavy (bad) spots and then spray entire roof with xjet.
Its like walking on ice, once its wet.
Wet down all surrounding vegetation-very good and expecially aroung the downspouts.