It's correct enough if the error disappeared. Those numbers appear conservative enough for a typical throttle.
The wider the spread between start and end voltages, the more granular the throttle range, meaning finer control is theoretically possible. But it's minor.
And you might be able to adjust out some of the deadband in the throttle by slightly lowering the "start voltage". But again, it's minor. Most of the deadband will be inherent to the mechanical workings of the throttle, only reducible by moving the magnet or restricting the return position with a pin or screw or something.