It doesn’t matter. It does not matter whether the change you lead is gradual or immediate (assuming there has been some preparation). Really, it is six of one and half-dozen of another.
When the time comes to implement whatever change you have been working on with your congregation – and working on is the imperative because people need to know it is coming and why it is coming – whether it is put in place gradually or rapidly there will be gnashing of teeth. All of us have a different capacity to embrace and assimilate change in our lives, and some people have so little elasticity that all change is equally painful. It is like standing at the door on Sunday morning after church and listening to five different people tell you on the way out what they thought of the hymns that day, some loved them and others absolutely hated them. What is the alternative? Never sing, or sing only what we know everyone likes?
The fact that change will cause discomfort and actual pain for some people is irrelevant, except that we need to be pastorally present with those who have strong reactions. Our task is to lead change not conspire and enable complacency. Too often clergy imagine that being pastorally sensitive to discomfort means protecting people from their feelings when what it actually means is being with them in their discomfort.
In my experience, going slow and being incremental with the pace of change requires just as much energy and in the end produces just as much angst as ripping the Band-Aid off all at once. The two primary issues are: are you interiorly centered so you can be present to the anger around you and still lead wisely and non-reactively; and, have you completed the preparation necessary for the change?