If you have a team of staff you should assign them purposes not congregations. In other words; staff “team” = Purpose based model is usually best.
The reason for this is kinda simplistic, but it seems it needs to be spelt out. The fact is, if you already have a team of staff working in one or more congregations, they are already specialising in different areas of ministry. And they are already doing poorly in other areas of ministry. That’s ok because Jesus gave them gifts to serve the body in their own special way. They are, by the grace of God, particularly suited to helping the church be and do particular things.
Secondly, either you are a team working together, or you are a mother’s club getting together to talk about your respective children. Some church staff talk like they are part of a team, when they’re not; they just get together to talk about their respective congregations and then go their merry way.
You have to choose first and foremost; are you going to be a church staff team, or a gathering of church staff?
If you’re going to be a team, then leverage that to the best of your ability for the glory of God. Use one another’s strengths, give some people responsibly for some things and others responsibility for other things.