Originally Posted by IronManlet
For me it is both. I don't really focus on a MMC when I do shrugs, for example. They're a pretty simple movement up and down, and you'll get a lot of benefits from overloading your Traps. On squats though? Or deadlifts? Good luck even trying to complete the lift if you don't do it right.
Right about the squat and deadlift. Those are the "dangerous" lifts and should be executed with proper form. Dipping the bar just a bit while squatting is ok imo, as long as back is arched.
The total back arch in deadlift is not a must for me as long as it is more arched than bend forward and that it stays tight.