CHANGING PLUGS IN A HEMI RAM

The plugs in our work trucks don't get changed unless it has a miss. A fleet of 25 or so Ford's. All of the 4.6 and 5.4 plug issues with threads pulling out and plugs breaking off ruled out plugs as normal maintenance for the mechanic. My old truck got plugs at 170k miles due to a slight miss at idle. My plug gap tool stops at .100 and the gap was bigger then that! Truck now has 238k and is soon for sale but still runs great. Mechanics old truck was a 6.2 F-350 and had 201k miles on the original plugs. Ran great when sold. I change plugs in my personal vehicles regularly but it's not necessary with modern ignition and EFI.