Assumed Objective vs Real Objective
The assumed objective of a strength exercise is to preform as many repetitions as possible with as much weight as possible. The this is actually the secondary objective.
The real objective of a strength exercise is to momentarily weaken the musculature, to fatigue it safely, quickly, efficiently, and deeply as possible for the purpose of stimulating the muscular growth mechanism with the least amount of weight in the least amount of time.
The above two sentences many sound slightly technical. To simplify, think of your strength workout in terms of you are there to do something to your muscles. You are not there to do something to the weights. The weights are simply the tool used to stimulate change. Keep your form as strict as possible and give your best effort. Embrace reaching muscle failure with perfect form. The key point is to fatigue the muscle as safely as possible. You can't get a better strength workout.