Taus is clearly the expert on this one. I have had far less experience with this than he since he kindly showed me the technique.
But I would say that I work in places with much less than stellar techs so I ALWAYS do all of the tilt and oblique myself, often live. Even when positioning looks great to me ( I try to keep pillow on the head only and off of the shoulder, make certain arm is not over stretched and patient is looking straight ahead) and I expect to need minimal adjustment, sometimes the initial image is way off, I need lots of adjustment and the correct direction is not clear initially.