I've been setting them up mechanically to where the travel at the carb is correct with the high end of the servo at 100%. The low end idle is less than 100% but at idle cut off the servo goes to 100%

Then I set exponential to get my throttle linearity the way I want it on the transmitter that doesn't actually have a programmable throttle curve

On the other transmitter, the throttle curve is programmable.