Like any exercise you can either vary from heavy weight with low reps or light weight with high reps. Something like the kickback is performed with lighter weight with high repetition. Very different from performing lets say a squat max.
With using the lighter weight you'll get much better triceps contraction. When performing the kickback you want to have weight that you can control. The kickback is a very short movement and the triceps are under tension the whole time. So usually for growth people will use bench press, military press ect. to super-set with the triceps kickback. To me the triceps kickback is one of the best triceps workout when done correctly.