If these engines are running richer than necessary because of the engine/carb design, I'm thinking that if the throttle is set to max static revs on the ground with mixture fully rich, then leaned to best revs, this would not be " fully rich" but would depend on elevation, pressure, density, temp etc? and should give best take off power on that particular day/place?
I'm not trying to rock the boat suggesting oddball ideas and I doubt if this would save anything worthwhile in fuel but, if the theory is correct then it would help me get my head completely round understanding this.