Example: We burst firecrackers at Diwali.
We burst firecrackers on Diwali night.
So does this mean "at " comes with occasions and festivals and "on" comes when we qualify them with "day" or "night" or "eve"?
We cannot say:"We burst firecrackers on Diwali." or can we say if the rest of the context clarifies that the firecrackers are to be burst on the day of Diwali itself?