There's been a sign crew working on putting up new intersection lights running two F550 6.7 trucks. Last week I went by them at ~7:00am and the trucks were idling. Came back by the house ~12:00pm and the trucks were still there idling.
As for idling my truck I use the remote start during the hot summer months and start my truck in advance so when I hop in it's nice and cool. I idle it at gas stations. I also use the timer on the remote start to cool the turbo off after a hard pull and then the truck shuts off. I idle at the deer camp a lot when we hunt. I think 25% of my total engine hours is basically idling.