Intensity builds immensity
You get as big as possible from becoming as strong as possible. When I started lifting I went into the gym with that ‘how much can I bench, curl, squat , and deadlift?’ attitude. That’s when I discovered how fast my strength could increase, and it made me crazy intense to get even stronger.
It's important that you do full movements for your triceps, because locking out is when your triceps work their hardest. Flex and squeeze at the contraction of each rep to hit all three triceps heads.