When populatyion measurment is very accurate

The Math Behind Gerrymandering and Wasted Votes

This Quant magazine goes into detail about Gerrymandering when voters always obey a preference. And the article makes sense.

But Gerrymandering occurs during census and populations change, hence there is uncertainty in voting preferences.  With a variation in preference of zero, one can do a lot. But when the populations are reasonably split, and the voting patterns slightly uncertain, then there is  moderate possibility that Gerrymandering works in reverse, the minority gaining more seats when districts are evenly matched..  

The minority then gets their Gerrymandered allotment every time, but occasionaly they win the more evenly matched district as a bonus. This is what we see in Texas, under even modest voter uncertainty, it is very difficult to insure the Gerrymandering does not backfire.