If you try to keep inflation flat (what the central bank is supposed to do). You can maximize score regularly in the 440k - 450k scores. I had constant very low unemployment and wages were very high.
In reality, I agree though. Just putting to 0% and letting it ride required far less prediction ability and it worked out fine.
It gets weirder, I just got a 442181 run out of a constant -0.50% interest rate.
It seems that the whole system tops off at a zero-effort 500K or something, and the best approach is to do nothing to mess it up, just keep things cheap and stay away.
In reality, I agree though. Just putting to 0% and letting it ride required far less prediction ability and it worked out fine.