I used to measure roofs for a solar company.
One time I went up on a very steep roof of a two story house alone, and without a harness. This roof plane was too steep to walk and the shingles were old and crumbing so I had to crawl so I didn't slide down towards the edge.
After about an hour of crawling around, the sun began to bake the shingles so they were too hot to touch, so I decided to bug out. As the roof was too steep to walk, the only way to the ladder was by scooting on my butt with my feet pointed towards the edge.
Every time I'd skid toward the edge my heart exploded in fear because it was hard to stop from moving. I had to use my hands to slow myself down and they were getting burned. All I could do was to rub my palms on my legs to transfer some of the heat, but they were being scorched. Imagine putting your hand on a hot frying pan full of grit.
I was completely alone, in a faraway town, with no one to call. It took forever to get to the ladder and by the time I did I was shaking and drenched in sweat. When I finally got back to the ground some people came out from a nearby house and said they saw me and were ready to call 911.
I had burn blisters on both palms and I never went on a roof like that again without a helper or PPE.