I support the lead musician, but with appropriate back-ups.
In our church, our main organist work schedule doesn't allow him to attend afternoon or other services outside of regular worship. we do have someone we can consider as a back-up. They sometimes switch up during the service (the main musician will play the chor selections, while the back-up will play during offerings or prayer.)
However, our back-up second musician is not as confident a player, so he doesn't like to play for the choir - he prefers the keyboard, bass guitar or drums.
As I am the person that usually has to arrange for a replacement musician; until our organists work schedule changes, I would love to have at least 3 musicians available, who can play anything.... so we can keep things interesting and moving forward; someone may have an affinity for playing worship songs, while another can handle more contemporary stuff...