36 x 12 is closer to vertical :) on a piece of paper, from a starting point, go 5 inches vertical and from same point go 6 inches out horizontal. That will give you the angle of a 10 x 12. When working on that pitch there would definitely be "toe boards" secured to the structure as a working platform. Come down grab a handful of shingles and proceed on. This was only on the right conditions, usually working in the morning. Anything steeper it was quicker to work of the bottom toe board as high as you could reach then secure another row of toe boards and move on up...
Lar