Cleaning the attic SUCKED and took a long time, about six 4-hour sessions. It was cramped, dark, and dirty work and I'm sure every hour I was up there took an hour off of my life. The reason the attic was so dirty has to do with the method of roof construction at the time the house was built. The wood shingles were nailed to 1x4 boards spaced every 12 inches or so which were nailed to the rafters. This left a big gap for debris to fall into when the shingles were replaced. And when they did fall they went in between the ceiling joists since none of the attic is finished. In its current state, the house has plywood nailed to the 1x4's with composite shingles secured to the plywood so the attic won't get full of roofing debris again when new shingles are required.
To actually clean up the dust and old shingle bits I scooted around on two small boards laying on the ceiling joists. Armed with a hand brush and dust pan I would fill trash bag after trash bag, bay by bay. I had very little head room and the only light source was a bulb at the end of an extension chord that I dragged along with me. In the end, I bagged 228 pounds of crap, including one desiccated rat. But even after I had bagged all of the trash the job wasn't over, I still had to get it out. As I had packed the bags too full, I ended up stomping the trash bags through the opening into the hall closet as Em waited below to catch them.
I took the picture above a few months after the attic was cleaned to show the tools of the trade and how cramped it was. If I had actually been cleaning I would be wearing a mask and be covered in dust.