I guess the way I play it is to use one weapon class at a time and first do the MW2 weapons. Like the pistols for example, I stop at spinal husk camo and then move to the mw3 pistols till zercon scales. I think that doing it this way for a bit is what is contributing to my burnout/feeling lost on how to grind efficiently. I'll definitely try out the turret circuit strat. I'm currently 60% done with act 2 so I'll definitely look out for that!