You can develop training scars but the more time spent handling, firing and shooting and moving the better off you are. Many many LEO ranges are static and do not prepare the officer/agent for real life. I don't know how many courses I've taken where I was taught a two handed grip with the pistol canted in close to the breast while moving around and then presented with a firm two handed punching out type move. It works great but I work at night and I always have a flashlight in my weak hand or I'm talking on the portable or using my weak hand to control a suspect, open a door, move a barrier...
Another point is people bringing up magazine changes and games teaching you bad form/tactics. How many of you non LEOs carrying spare ammo when out and about in public? For that matter how many of you LEOs carrying extra ammo off duty?