From a recent study:
Approximately 3/4 of their growing churches were being led by pastors who had been in their church more than four years, while 2/3 of their declining churches were being led by pastors who had been in their church less than four years. Their conclusion (with which I agree): Long-term pastorates do not guarantee that a church will grow. But short-term pastorates essentially guarantee that a church will not grow.
It takes years to develop relational and cultural competence in a ministry context. Fruitfulness in a ministry context often doesn’t begin until after the 5th to 8th year. If pastors have a pattern of changing locations every few years, it is usually an indication of a problem and generally limits his ministry fruitfulness. Churches that have a pattern of changing pastors every few years also are likely indicating dysfunction of the church and limiting fruitfulness of ministry in their environment.
This concern is even more relevant when working cross-culturally. Churches and individuals that are serious about reaching the nations but primarily use a short-term project strategy should consider changing their focus to long-term engagement in a specific place.