I bought a set of 4 roof jacks 40 years ago for $5 at a yard sale. Might use them once in every 6 years, but they have well paid their way. I hired a firm to roof my last house because it was not only steep, on the back side it was a forty foot drop to the ground. They were tied off with safety harnesses and used roof jacks. But they were accustomed to such work and could walk up right in places where I would be crawling and shaking in fear.
When i was about 17, I slid off a quonset hut roof and landed on some cedar trees. I was only shook up, but learned to be very cautious.