Automatic Performance adjustment

I was curious about the Performance Survey last week.  I got the impression
that the majority favored manual tuning of the system vs. automatic
performance adjustment via QPFRADJ.  Personally, I have been a fan of
QPFRADJ ever since it began using less than 1% of the CPU.

1.)  What can I do to manually tune the system, that QPFRADJ cannot do
automagically?

2.)  Why would I want to spend time manually tuning the system when I can
set up the basics and let QPFRADJ take care of the day to day(or hour to
hour) fluctuations?

Or does the majority favor setting QPFRADJ to 2 or 3?

Scott Ingvaldson
AS/400 System Administrator
GuideOne Insurance Group