EGT shutdown temps
 

This is a question for those who have an pyrometer on there cars. I've heard that you should let you car idle for a few minutes after running at highway speeds before shutting off the engine on turbo cars.
Some vids I've seen on show the EGTs drop pretty quick. How long does it take generally for the EGTs to drop to a reasonable level idling after highway speeds?
The reason I ask is I run about 65 on the way to work but work is right on the highway so I usually let it idle for a minute or too before shutting down. I was wondering if this is sufficient.

15 seconds is more than enough. The deceleration from highway speeds does a large amount of cooling.

The manual I have
 

recommends idling for 1-2 minutes after highway or hill climbing.