And then I contemplate that the rhythm is the king. The rhythm of the song dictates what the voice does.
It's like that with writing as well. Sometimes a slow, meandering flow is appropriate for the story/article/poem. Other times, an intense, more hammering rhythm is called for.
I'm leaving you with a Ruthie Foster video, and giving you a link to Jennifer Brown Banks' blog, 'cause in a comment she (Jennifer, not Ruthie) reminded me of how much I love Foster's singing.