I always just go on that NPC's are made in IC, people adding to a character when they see fit. Just like how a story introduces characters. For instance:

Faye looked over to James, he was known as the heaviest drinker in the caravan, even able to outdrink Faye. James stood up and from where Faye sat she saw the many tattoos across his bare muscular chest. He had told her once that they meant something spiritual, but Faye had forgotten since then. James grabbed a large axe and began to chop wood, it was one of his main jobs after all.

In this story paragraph I have explained a character withouth a C.S
His name is James
He is a heavy Drinker
He has tattoos that mean something spiritual.
He is muscular
He chops wood for the camp

All that without needing a C.S 
I feel this way of control means that the imagination of the writer can flow into the characters, creating NPC's that they can control for a few sentences.