Depende se você encerra o servidor com ou sem o NOWAIT.
Em MSDN :
Unless the WITH NOWAIT option is used, SHUTDOWN shuts down SQL Server by:
- Disabling logins (except for members of the sysadmin and serveradmin fixed server roles).
- Waiting for currently running Transact-SQL statements or stored procedures to finish. To display a list of all active processes and locks, run sp_who and sp_lock, respectively.
- Inserting a checkpoint in every database.
Using the SHUTDOWN statement minimizes the amount of automatic recovery work needed when members of the sysadmin fixed server role restart SQL Server.
Quanto a encerrar COM NOWAIT:
Optional. Shuts down SQL Server without performing checkpoints in every database. SQL Server exits after attempting to terminate all user processes. When the server restarts, a rollback operation occurs for uncompleted transactions.
O padrão é aguardar o término das transações atualmente em execução (NOWAIT é opcional).