I think you’re wise to question whether there is one single model of leadership advocated by the Bible. I think the single-pastor model can be good, and it can be harmful – as can other models. I think structures evolve over time – as they should – sometimes to meet needs, sometimes as a reflection of a cooling or warming spirituality, sometimes for the sake of survival or efficiency. So, I’d put leadership structures in the area of “wisdom,” not “rules.” The best ones are ones that can change. I write about this in The Church on the Other Side.