The walking motion obviously adds the normal walking speed on top of whatever the motor puts in. On top of that I bet most of the forward rolling motion actual

The walking motion obviously adds the normal walking speed on top of whatever the motor puts in. On top of that I bet most of the forward rolling motion actually comes from you yourself putting in force by walking, not from the motor pushing forward. The wheels then just continue coasting. Most likely the motor just providing balance and preventing the wheels from rolling backwards as you push forward, like an advanced version of the under grip on cross-country-skis. Planting the feet to only rely on motor force would significantly reduce the distance and with both feet next to each other increase the likelihood of face plants when hitting small obstacles.