In your opening you say,
"For reasons unknown, many users believe they should repair permissions immediately before, immediately after, and sometimes during (by intercepting the restart) system updates."

and

"Apple does not recommend any of these mythological means of avoiding update problems. They are more likely to cause problems (as the orginal posting showed) than to prevent them."

Then you go on to describe your upgrade process:

"2. Repair permissions. 3. Run DiskWarrior and perform repairs if needed."

What are those two even doing there? If you are having no system problems, don't be messing with your permissions. If you *are* having problems, resolve them *before* you start messing with upgrading...

Sure, keep frequent backups, especially before changes, but your upgrade path should consist of 1) start with stable system, 2) run the updater.

No kidding. Here's how I do it:

Accept the updates offered by Apple Software update.

Been doing this for 5 years of OS X use and have never had a problem.

Some people are just paranoid.

I also just install updates via Software Update. I only run permissions repair when I get bored or when I have reason to believe it might be necessary (as in after the last Flash update, which as reported by others did screw up a couple of permissions).