Dristhis, what does this mean? As I understood it so far it means to look in a direction without moving the eyes. It is not necessary to realize nothing else. It is possible to focus the gaze but to realize at the same time what is going on next to me. To have a peripheric view in addition to a focused gaze is possible. (To see the fellow Ashtangi next to me is possible.)
To exercise drishti is much more than not looking around observing the other aspirants. It means to keep the eyes quit. There is a connection between eye momement and thinking. It is called "rapid eye movement". You can make a test. Ask someone to imagine a green elephant and you shall see how the eyes will move. So thinking and eye movements are connected. When keeping the eyes quite, thinking becomes more difficult. And this is the goal of the dristis.
Drishtis help to control the mind. The technique is keeping the eyes quit, without movement. Yoga trains the body and the mind.
I am in a hurry now. Must stop writing about this interesting topic.
Picture: Also Indians buy water to stay healthy. Not every Indian drinks tap water.