Once again today, I was asked by a developer, how you can "turn off those annoying completion time messages in SSMS".
A few releases of SQL Server Management Studio (SSMS) back, the product team decided that we'd all like completion times shown in the Messages output tab. I don't share their enthusiasm for them.
For a start, a completion time was already shown here in the Properties window for the query, along with much more info:
So it really was quite irrelevant. Worse, I often use the output of the Messages tab as text for scripts, etc. The last thing I wanted were a bunch of completion times sprinkled through those.
Initially, you couldn't turn it off either. Fortunately, the team listened to us all complaining about it, and they fixed it.
Single Query Window
If you want to disable these messages for a single query window, you can do it here from the Query menu, then Query Options, then Advanced.
As the Default
If you want this disabled by default, you can do that from the Tools menu, then Options, then Query Execution, then SQL Server, then Advanced:
And say goodbye to those messages.