It is human nature to draw from experiences to make sense of our surroundings. This holds true in life and performance tuning. A veteran systems administrator will typically tune a system different from an Oracle DBA. This is fine, but often what is obvious to one, is not to the other. It is sometimes necessary to take a step back to tune from another perspective.
I recently have ran across a few cases where a customer was tuning “Sorts” in the database by adding memory. Regardless of your prospective, every one knows memory is faster than disk; and the goal of any good tuner is to use as much in memory as possible. So, when it was noticed by the systems administrator that the “TEMP” disks for Oracle were doing a tremendous amount of IO, the answer was obvious right?