How often to IPL?

A recent discussion on LinkedIn discouraged IPLing frequently. And they
have a good point as each IPL resets your query optimizer and throws out
all temporary indexes. The catch was basically you should reduce IPLs for
PTF's, etc.

Here's the catch though: How often should you put on the PTF's? I think
we're better than most shops because we put on the latest cume and groups
on a quarterly basis. And there's always those shops that want to be some
lengthy amount of time behind. But how do you explain to your stakeholders
that you were notified that you were potentially exposed because you don't
have this Java group ptf on, or you don't have this level of firmware on,
or this Hiper group on? Do you tell them:

- "I know of the risk that we could lose a bunch of confidential
information but what if there's a flawed PTF and it causes issues?"

- "I know that IBM found an issue with the current level we're at and
issued a fixing PTF but what if that fixing PTF causes issues?"

- "We've been on this level for two years now and nothing has happened so
why fix what isn't broken?"

We're finding out that newer certification levels are requiring you to put
patches on much more frequently than most people do. And, frankly, it takes
less disruptive time to patch an IBM Power system than it does a Windows
Server.

If there's an incident, and management finds out that you were notified by
IBM notifications and you didn't put on the patch, are you going under the
bus?