A team calendar needs an ownership layer a solo calendar does not
A single creator's calendar only needs to track what and when. Once more than one person is involved, the calendar also has to track who is responsible for each piece at each stage: drafting, review, approval, publishing. Without that, work stalls in an ambiguous middle ground nobody feels responsible for moving forward.
Build in a review stage with its own date
A calendar that only tracks a final publish date, with no distinct review or approval step built in, tends to produce last-minute scrambles when a piece needs revision. A defined review stage with its own timeline gives real room for that back-and-forth without threatening the publish date.
Keep the calendar visible to the whole team
A calendar only one person can see creates a bottleneck where every status question has to be routed through them. A shared, visible calendar lets anyone on the team check status directly, which meaningfully reduces coordination overhead as a team grows.