In our music team, we do have a lot of back up singers. However, not all of them are singing in front of the stage. Every week, during our church Sunday service, they have a scheduled back up singers who will sing during that week. We always have a our band rehearsal before we do our actual stage performance. When we have a new song that needs to be rehearsed,we familiarize its tune and melody first.... 

My wife has a busy lifestyle and evidently, she have no time to even take into consideration in practicing for a vocal preparation. But I  advised  her that she should do it every time she performs in front of the stage. If you sing on a regular basis like her, your vocal chords and throat muscle groups are consistently being stretched and exercised. And like every muscle there are keys to holding... 

Well yes it is. This is our life as a member of the music ministry . I am actually the song leader of our church. As the worship leader, I am the one who will choose the song for our Praise and Worship service every Sunday. Sometimes I find it hard to choose what song we will have to play and sing with since we have to fit it for the whole congregation where all the members can familiarize the song....