Ideling can lessen the oil flow to the turbo. While it is required for a couple of minutes while the engine is hot, just after pulling off the interstate, it is not required otherwise.
Ideling a newer F-350 is not recommended in the owners manual.
It is also illegal in many states to idle over 4 minutes. McDonalds has put 3 minute timers on all their trucks in California, so they stop the engine after 3 minutes. But that is not handy in a intersection! My buddy now stops about 30 feet back, then after 2 minutes puts his foot on the gas to pull up a bit, to avoid the timer shutting off the engine at 3 minutes!
Now many big rig trucks will use a 2-3 KW electric generator, or APU that has a freon compressor on it to run the cab A/C while going down the road or while stopped for the night.