Every piece of music – from “Mary Had a Little Lamb” to Beethoven’s Symphony No. 9 – has some sort of shape. There is a rise and fall of some sort, whether you are talking about rhythm, dynamics, melody, harmony, texture, etc. (Aside: Texture is basically how all the different parts interact.) As a leader of musicians, it is your responsibility to see to it that your worship music has an overall shape.
There’s no hard and fast rule about this. Just because the bridge is the “biggest” part of one song doesn’t mean it’s the biggest part of every song. It’s not always the chorus after the bridge, either. Just because the musical shape is one way on so-and-so’s recording doesn’t mean that you have to copy it.
What you don’t want to happen is that you start it and the entire song is flat. It never goes anywhere. It doesn’t build. It doesn’t wane. It just flops on all the way through… Lazy as fuck. And don’t go blaming it on the drummer, either. It’s not her job to control the entire musical shape. That’s your job.
(Don’t get me wrong; A sure way to tell if your drummer has never listened to the song and is reading the chord chart down is if he or she plays it “flat” the whole way through. After you’ve played with enough musicians, there are certain tells for all of the instruments about who has and hasn’t prepared.)
The more familiar a song is, the greater the likelihood the band may play it flat. Do not let them do this. Your congregation deserves better. God deserves better. Don’t call in your worship.