One word .............. airless.
More prep time, and some overspray, but hoooooey, it covers. A helper and I
painted a block wall 400 feet long in less than four hours. That four hours
included set up and clean up. Many people swear at airless sprayers, but I
love my Graco XR7 that I got on ebay for $260. They are also great for
painting interiors, particularly popcorn ceilings. On walls, one sprays,
and another rolls behind him with a fleece roller to flatten out and give a
nice stipple. Comes out very uniform.