Adjusting the wheel up or down doesn't itself change the force applied by the wheel on the blade. However, that's not the point - the point is, the higher you start up the blade, the more vertical travel the wheel has to make to reach the bottom of the blade, and that puts more load on the spring (shown top center in this pic below). This causes more force (Hooke's law) to be applied to the steel. As you push the wheel down, that spring in the pic extends - the more it's extended, the more force it's applying on the object extending it.
So the whole point of the height adjustment is to allow you, for any depth of steel from banana blades to brand new Step, to find the height that allows the wheel to start a small ways up the toe or heel, and still smoothly travel the length of the steel with optimal force applied.
If you go up too high, and you have newer LS3/LS4/Step with 10" radius that hasn't been rounded off - you will be applying more than the optimal force on the blade, and you will hear this in pitch changes 2/3/4 times down the length of the steel.
In my experience, dropping the wheel another notch or two will reduce the vertical travel of the wheel, and therefore reduce the friction and eliminate the 'skips', resulting in a smoother constant-pitch sharpening pass, with no skip/stop marks on the finished hollow. A perfect finished hollow should look uniformly polished toe to heel all the way with no interruptions when held under the light.
Again, in my experience, if you are getting pitch changes and non-uniform looking hollows (from a polish POV), try lowering the wheel and doing a couple more passes and see how it then sounds/looks. It probably makes next to zero difference in performance on-ice, but sharpening blades is one of those things where we all just strive for and crave perfection, isn't it?? 🙂
colins