<p>Through my SharePoint career I've set it my policy to install:</p>

<ul>
<li>Service Packs: Install as soon as they've come out.  After evaluating on a test box, install to production
<li>Cumulative Updates, Hot Fixes, etc: Install only if the need arises (for example we run into a problem one of them fixes).

</ul>

The current person I'm with disagrees and likes to install everything the moment it comes out.  I'm curious to see what everyone else here thinks of that policy and can point out times they had experienced when installing a Cumulative update for SharePoint was a lousy idea for them.

Long story short, how to you go about setting up patch rules for SharePoint? Specifically what steps do you take to implement a Service pack, Cumulative Update, etc. in your farm?  How do you evaluate?  What safeguards do you take against Service pack failure, etc?