This morning's progress was definitely better. I only worked for an hour and a half because I had some writing to do, but I got more accomplished than all of yesterday morning.
The secret was Chris's clothing steamer. It definitely helped to make the sticking backing come off the wall in larger pieces with less struggle.
So at least now I have the whole landing done and part of the stairway.
Little by little, I will remove you, wallpaper. You are no match for me and the steamer!