Controlled crying - yes or no

I don't have children of my own yet but I'm currently baby sitting for my brother in law. My brother, who's a registered nurse told me that we don't have to always give attention to our niece whenever she's crying so that she can also exercise her lungs when she's crying. He said that its not bad for the baby. Sometimes our adorable niece will wail so bad that you'll think she got hurt or something but will stop automatically when you carry her and smile. Because of this we end up trying to figure out when she really does need to be taken care of or she just wants to be carried which we want to avoid.

I think controlled crying is a perfectly fine method to deal with a child. I've seen a lot of children pretend cry, with all the sound effects and motions of crying but none of the real tears, when their parent denies them something or reprimands them. So I think that method is especially effective when that type of problem comes up because it helps teach the child that crying will not get you your way every time