excessive idling when cold can build up more carbon since its running rich when cold. with that there is the problem of excess buildup on the 6's where you have to clean that crap out so you dont get detonation (spark knock) and if you raise the rpms right from the getgo it will warm faster and have less carbon buildup.
I take off about 5-10 seconds after I start the car and have a mile where i can really drive easy before i have to accelerate to 55mph. To just fire it up and go blasting up to and at 55 just doesnt sound healthy to me.