Few years ago they put a new roof on the 2 story office next door. 2 couldn't have been more 18 year old kids packed all the shingles up by hand. They couldn't have been much more than 5 foot tall and 120 lbs but they threw 2 flats of shingles over a shoulder and started walking up that latter, no hand on the latter. I watched for a few minutes. Them kids were like machines.
I watched some hot tar roofers doing it that way years ago. Ladder against the edge of a warehouse, bucket in each hand and up they went.
Years ago I worked nights running a press. Had 2 meth heads on my crew. One night it was slow and they decided to replace lights in the ceiling. That company had no man lift so these guys put a 10' ladder on a stack of pallets and up the younger one went via forklift. That stack was like a slinky, back and forth. I couldn't watch anymore for fear I'd have an image in my head for life that was ugly. I went outside for a smoke break. The kid survived and the shop was bright.