Steve wrote:

It is the shoes/boots?

Part experience, part shoes. I have walked a 6/12 pitched tile roof for over 12
years now. The first half dozen times it was very spooky. Now, it's no big deal.

Critical that the roof be dry and the shoes be rubber soled. Leather is a recipe
for disaster. Kerp yourself vertical or tilted slightly towards the peak. Walk
across the pitch on an angle, not straight down.