There's another flaw -- in Dilbert's logic.
Let's say the top of the range that can never be achieved is one million. 115 percent below that would mean he is paid negative one hundred fifty thousand. This is clearly not his salary.
There's a flaw in your example. The highest that 115% of the midpoint can be is the high of the range. If you're above that then the midpoint must be adjusted. Since these seem to be set salary ranges for positions, I would assume that the only option once you hit the high is to move up if you want to make more.
I once worked with someone who was making the most she could within her position, so I know it happens.
Oops, I just reread and saw the "iterative" and after that I'm not really sure what you're trying to say. They have a range, it has a midpoint, you can't go over the high of the range. This stands.
Actually, 115% of the midpoint CAN be good (but a little iterative...). Example:
Lowest salary is 100, highest is 120, midpoint 110, 115% of that would be 126.5 - so the highest salary would be 126.5, midpoint 113.25, 115% of that would be 130.2375...
You should end up at about 135.29