I almost never shoot with a straight up and down bow, but, I do practice that shot. My face has to be at the same angle as my bow. I can't keep my head erect and cant my bow. My head, shoulders, and bow arm follow my bow-from vertical to horizontal.
I practice with my bow parallel to the ground, whether I'm standing, sitting, kneeling-on the ground or in a stand. 2 years ago, I shot at a fox that was 20 feet away. I was on my knees, my chest was maybe a foot off the ground and my bow flat. He got a haircut because I didn't pick a spot!!