Not to mention,.every job can be different,..some I can treat with a house wash mix DS'ed,..others I lay on roof mix,...and when I run into the "big green" dots of mold,..I put on 12.5%,..these type spots are on sidewalks more than driveways in my experience. But then,..we have predominately asphalt driveways here.
Flagstone patios and walkways are the hardest thing to clean,..it takes multiple applications of 12.5% and NAOH to get the spots completely out. The first round removes the green top of the mold,..leaving behind a black spot,..then it has to be treated and let dwell forever it seems,Ha,Ha,..
As many do,..I pre-treat concrete before I even start the house wash or roof clean,.or deck or whatever,..gives it plenty of time to work,..
Always a good idea to put safety cones up anywhere that's been treated as to avoid foot traffic in and out of the house. Usually isn't an issue. But sometimes the mailman shows up or UPS,..nice to keep them out of the 12.5% if possible and walking through the grass.
Jeff