Remember that right thrust is only properly set at one specific power setting too. Every other second of the flight, it is wrong. Check out most people's planes, they have right rudder trim on the ground because it is trimmed for full power loops. In any other situation, you have too much right and the only way to properly fix that is to have the rudder trim (mix) vary with power. Planes with large electric props will need right mix with full power and actually a little left mix with idle.

If you want to get more critical, you also need left aileron with high throttle too and right aileron with low. Not much, maybe 1-2% but it is there.

People that boast they have a plane with no mix don't understand that is not always an optimum situation to have.