I just wish I could do it a bit faster, but if I do, all I get are lots of little stones all over the place.
A note about Roofing granules: they appear to be a manufactured product rather than crushed rock. I'm going to figure a way to darken them for the yard tracks. I'm going to try using a heavy alcohol/India Ink wash as the wetting agent. On my trial piece it did darken it a bit. They make black granules, but the roofing supply place where I purchased this didn't stock it.