The spreadsheet reports the degrees of movement the motor must move. This is not the same as difference in azimuth along the horizon. The axis of the motor is parallel to the axis of the earth, no matter what your latitude is. In the top-down view, you are looking down on top of the earth's axis, as well as the axis of your motor.
To exaggerate the angles as you used them, think if you are at 84 degrees west at the equator. Your azimuth from 83 to 85 would be 180 degrees. The real difference in position as seen by a motor is only ~2.x degrees.
To exaggerate the angles as you used them, think if you are at 84 degrees west at the equator. Your azimuth from 83 to 85 would be 180 degrees. The real difference in position as seen by a motor is only ~2.x degrees.