Don't waste ANY energy
If you're a client, I hope you feel I say this almost too often... "Make every repetition count!". However, I should probably invest equal amounts of time explaining what I mean, which I hope to do here. If you aren't a client of mine, I hope this article emphasizes how important it is to think about your exercises - even before you get to the workout, but then especially as you're doing the movements.
Every exercise involves moving a resistance through a range of motion. Sometimes you want to maintain a full range of motion, sometimes you may want to focus on a certain portion of the movement.
Even on exercises where you begin from a full rest position, you want to tense the working muscle from the very beginning.
Continuing with the "Hammer Curl", I would already tense the elbow, forearm, biceps and shoulder muscles before I even move the weight. Then, as the movement contracts the muscle, I maximize this intentionally at the top, before releasing the resistance into an eccentric phase.
I will leave it at this for now, as my goal was inspire thoughts. Consider each repetition during your next workout. Tense the muscles at the start of the movement, instead of waiting for the range of motion to decide when the muscle tenses. Then, take a moment to squeeze the muscle at its peak contraction point before you release it again. You won't be able to go as heavy this way, but you will add a significant amount of effectiveness if your goal is to 'work the muscle'.