In my personal experience most of the tuning of a database happens in tandem with tuning the application. E.g. you find a set of problematic queries and then go

In my personal experience most of the tuning of a database happens in tandem with tuning the application. E.g. you find a set of problematic queries and then go back to the application to see if they should be fixed or if the database is incorrectly tuned. Quite often it is a mix of both, and just automating most of the tuning only just changes the role of the DBA, not does away with it.