Hmmm. I wonder who decides?
My first question on an aircraft question is always: "What does the flight manual say?" and if there is no joy there: "What does the engineer say?" and THEN asking a wise instructor.
As to leaning on the ground, two of our C152 trainers are totally different in ground handling. One need full rich to taxi, and the other half mixture. But that has been decided in talks with owner and engineer. Fuel flows at those power settings are very small to be unnoticed in the bottom line.
ECT?