For all other worktable sorts, the worktable is unpartitioned when the step that created it completes. Worker processes are assigned in the following way:
If there is only one device in tempdb, the sort is performed using two consumers and one producer; otherwise, one consumer process is assigned for each device in tempdb, and a single producer process scans the worktable.
If there are more devices in tempdb than the available worker processes when the sort starts, the sort is performed in serial.
