Some clients ask me. The answer: “no”. Each situation and story is different. I jump back and forth between high level story line design to graphics design details to numerical analysis.
Is this the best approach to presentation design? Probably not, but I can pull it off for a two reasons: many years of experience, being a 1-person operation, mostly having 1 contact person at a client, and having clients that self-select, i.e., if they uncomfortable with this approach they would not choose to work with me.
As soon as you deal with multiple people, at different levels of experience, and an agency that tries to scale up, there is no escaping to a formal process with specific end products at specific times.