Did you feel tired with your Scrum Board which has over 20 columns and the flow is too complicated? If yes! It's the right time for you to look back and remove the complexity. The reason we apply Scrum is dealing with complexity, not making it bigger!
From my old post about "Definition of Workflow", some people asked me to write more detail about "how to build a workflow" and "how to apply it" to maximize the value of a team.