Unison is underrated. Often times when we lead music, we see singing in unison as just that thing you do to introduce the melody and then jump away from so you can get to the harmony. No. Unison is a distinct creature onto itself and depending on the musical context can be vital in setting up the song’s “big moments.”
Yes, harmony is “a step up” from unison when building a song. On some songs, you don’t want to just build everything by gradually rising through the levels. It can be a lot more powerful to keep it down – in unison and intensity – and then hit that loud dramatic fully-harmonized explosion like a smack right in between the eyes. If you gradually rise up, though, that “explosion” is just everyone playing as loud as they can.
Don’t call in your worship. You may miss some real opportunities.