Wash the bike? Um, nope. For road bikes, I wipe down the frame only when the bike is up on the stand for service. Otherwise, I let the frame alone.

Keep the drivetrain clean and lubricated? Um, certainly. I do this monthly or so, but I ride (road) on clean paved surfaces, not as the OP does. If roads in India are anything like the scenes I've seen filmed in the cities and countryside in India, then I'd likely not even ride a road bike at all.

For a mountain bike, I may rinse it off if the crud has built up so thickly that it affects the exposed cable runs. This might be once a year or after a particularly cruddy ride. Of course, long stream crossings do wash off some of the crud for you.