From my experience I will tell that T.Nagar is the busiest area I have ever seen. As it is main hub for jewelery and textile shops, usually there will be heavy crowd in the streets of T.Nagar. That too particularly on festival days, we can't enter into T.Nagar.
Practice makes perfect..
It is very difficult to shop during the festival time such as diwali, pongal, christmas, etc.
Such is the craze among people that it is the busiest commercial place in Chennai.