After extensive military training I've found the best alternative to simulators is to exhert physical activity in between shooting sessions. We had a ex drill instructor in charge of our PT and he would call your ass out in a minute if you were slowing down. After about 5 minutes of pushups, planks, sprinting in place, jumping jacks, bearcralws, and yelling you were begging to shot your rifle just to catch a break.
This was of course in the deserts of kuwait where noone was around to catch a stray when we were shooting while fatigued. I never really lost shot placement but a few individuals couldn't maintain a safe grip/pattern in shooting so we quit before someone was hurt. We went back to simulation ammo to keep us frosty. We weren't as tired as doing the physical activity but getting shot at with simulation rounds is damn stressful as we had no way to wash our uniforms for a few days
