You create a new intent when you have a new question to answer. i.e. do you want to play soccer?
The intent there is to find out if someone plays soccer so you would create an intent for say "soccer" if you already have other sports answered in a similar way. So all future variations of the question of playing soccer i.e. "bro do u even soccer"? would map to the soccer internet
A new story is for an entirely different subject or maybe a variant of the same question that is sufficiently different enough i.e. how long have you been playing soccer?
I was lost when I first got into Wit too and didn't know where to start.