I've seen this in the villages in Tamilnadu where the bullocks has bells around the neck, the bullockcart will have farm produce or bags loaded with a kerosene lamp hanging below between the wheels. I have taken rides in these after coming back to a smaller village or after a weekly village fair and tent movie theatres. The rhythmic jingling of the bells, the steady pace is very soothing and we can easily go to sleep. What Venkiteswaran sir says is correct, the bullocks will stop and the regular places for the farmer to wake up, give it a little hay while he has come coffee or tea. I think this is the way they are trained from the beginning by the farmers family. In fact, if the bullock has stopped, then there is something wrong, in olden days this would mean a predator or strangers on the road. As a child, I've seen some places near the village square where some water will be kept, the bullocks and cows will find their way, have a drink and move on.