For the type of clients I work with, a full "campaign calendar" isn't something they ever need to see. They usually just see the final email. And that's intentional.
I used to collaborate on calendars early in my business — pitching ideas, waiting on feedback, adjusting dates. It added a layer of approval that didn't actually help the clients I work with. Most of them hire email support because they don't want to manage another planning document. They just want the channel handled.
So now the process is simple and internal: we plan the campaign calendar, keep a bank of ready-to-send emails, track product launches and restocks, and the client generally just sees the finished email — not the entire roadmap.
It keeps things moving and avoids the bottlenecks that happen when founders have to approve every idea before it becomes an email.