One thing to notice is how the harmony parts are used in each song. Some use harmony almost all the way through, while others use harmony kind of like punctuation to enhance a point, and still others use the harmony as ambiance.

When thinking about when to use harmony in worship, it is important, in my opinion, to make it accessible for the congregation, as well. So unless a song is meant to be a “special” that the congregation will not sing, think about keeping the harmony simple, somewhat predictable, and still in a singable range. There are plenty of opportunities to get fancier with the harmony, but I do think we generally want to avoid making the harmony so intricate that people would be afraid to sing it.