I don't understand what you mean by "should they be controled"? My answer, yes, I do NOT want 400 lbs just dropping to my chest and bouncing off of it. Nor do I want to just "plop" down doing squats and hope my knees can bounce the weight back up.
No matter how fast or slow, you still need to control the weight. You're lifting the weight, don't let it lift you.
JW