This is likely a temporary snapshot. The policy executes its scheduling cycle every sessionSchedulingInterval and updates the planned scheduling information once per cycle (default 500ms). The planned scheduling information includes the session's "demanded", "deserved", and "assigned" values that are visible in the "soamview session -a" output or the Platform Management Console's "Symphony Workload > Monitor Workload > Sessions" tab. As the SSM receives new tasks from clients and task results are received from the services/SIMs, the session will report status changes for these newly-received tasks and task results. However, the planned scheduling information will not change until the next scheduling cycle executes.
Another reason why a session demands more resources than required for all of its pending tasks may be due to the MinimumServices policy configuration where the session is requesting its configured minServices.
You may notice inconsistencies in the display of DESERVED" value and session priority. The SSM scheduling policy takes a snapshot of the sessions (this includes outstanding workload and session priority) when it begins the scheduling cycle. The "DESERVED" value is calculated based on the snapshot. The displayed priority is the actual priority of the session. As a result, the "DESERVED" value may seem incorrect when juxtaposed with the actual priority of the session.