Not quite: the contact pattern on the valve stems starts on the inner third of the valve stem and then sweep outward across the center of the stem to the outer third at HALF lift, then back to its original position at FULL lift; it will be centered on the stem tip at (nearly) 25%, and again at 75% lift.
The sweep distance is greatly affected by the ratio of the long (valve-side) lever divided by the net lift at the valve: short rocker (LA) + high (.700") lift = long sweep, long rocker (hemi exhaust) + short lift (.500") = short sweep, etc. This is not an adjustment or alignment, and the cure is a different rocker and lots of work.

Mid-lift is only available if you're using Jim Miller's rockers, it's a patented feature and does not exist unless you make it yourself. Setting the valve-side geometry to 1/2 up, 1/2 down @ 90 degrees just moves the error to the pushrod side. This is frequently an improvement, but that's all you can do - bump the discrepancy back & forth across the shaft axis.