Nobody on a worksharing team is actually editing the same file at the same time — and that's exactly the point.
Picture five engineers "in the model together" and the natural assumption is that all five are clicking around inside one shared, live file — the way five people might co-edit one browser tab. That's not what worksharing does. The central model is a single copy stored on a server that no one opens or edits directly during normal work. Each team member instead opens their own local model — a full cached copy on their own machine — and edits that. The two copies only reconcile with each other at deliberate moments, through Synchronize with Central (SWC).