It might be more clearer to turn the wheel twice then you get either 9.4 turns or about 7 turns of prop , bit of white paint on prop will help count
Be careful not to overllok that the differential gears are also involved.
One way to see this is to split the motion into two parts.
Imagine both wheels are off the ground and free. Turn the prop in the normal direction by 4.7 (or whatever the final drive reduction ratio is) turns. Both wheels will have turned forwards by one turn, and the differential gears will not have turned relative to each other.
Now, hold the prop still, and turn one wheel back one turn. The other wheel will turn one turn forwards, owing to the differential gears.
At this point one wheel will not have turned at all, and one wheel would have turned twice, i.e., this is equivalent to one wheel on the ground,and one wheel free.
So, with one wheel one the ground, it takes 2 turns of the free wheel to get the final drive reduction ratio number of turns at the prop shaft.
Another way to see this is to imagine the differential gears directly. The sun gear of the fixed wheel remains stationary. As the free wheel is turned, its sun gear turns the planet gears which "walk" around the fixed sun gear. As the motion to the crown wheel comes from the axle in the planet gears, this moves half as far as the pitch point of the moving sun / planet gear mesh.
