The real difficulty is context-switching, not content volume
Managing 5 clients does not mean 5 times the content work in isolation. It means switching between 5 different voices, sets of priorities, and approval processes throughout a single day. The cost of that switching is usually the bottleneck, more than the raw amount of content produced.
A clear approval process prevents the most common mistake
The failure that damages an agency's trust fastest is a post going out for the wrong client, or without a client's sign-off when one was expected. The defense is a consistent, explicit approval step per client, rather than an informal habit that varies by account. Carefulness alone does not cover it.
Separate workspaces beat one shared calendar for everyone
A single shared calendar covering every client's content invites exactly the mix-up that damages trust: the wrong logo, the wrong voice, a post meant for one brand going out under another. Fully separate workspaces per client or brand, each with their own connected channels and calendar, remove that category of mistake structurally, instead of relying on a person catching it every time.
What clients want to see reported
Most clients care less about a dashboard of every available metric than about a few numbers tied to what they asked for at the start of the engagement. Reporting built around the goals set with each client reads as more credible than a generic template applied identically to everyone.