Just had the same question few weeks ago and asked my mechanic about it. He however suggested that if my car is in a complete stop for a long period of time it is better to switch to N even if your only stopping awhile.

I am driving a Waja 2003 AT model. When I feel the traffic light gona be green soon I just leave it in D otherwise if long stop I will switch to N. However I am still not sure if this is a good driving habit.

Any insight on this matter would be very helpful