For what it is worth, I just re-did my 8' C-Band using Satsig numbers. I did not touch my true south adjustment, just the elevation and declination. When done, I was getting both ends of the arc, where before I was not. Now, I'm not perfect either, as I can't get the mux on 137, but can get the radio stuff on 139, and during the day I basically lose the Luken channels and may or may not get the PA cable channel to the east during the day too. So, I still need to do some tweaking.
I had the same thought as you, when I looked at the numbers. Then, thought, what the hey, give it a try, I can always go back to the latitude and larger declination. We also have to remember, that we are shooting for an optimum setting, because unless we have everything exactly perfect, there is no way we can get maximum performance out of a polar mount.
My $0.02 worth.