I believe the main reason why bodybuilders show weak points in their biceps is that they do their biceps exercises incorrectly. One must master proper technique, employing as many shocking principles as possible.
Doing this and training your biceps like this, you will be much less likely to have problems in this area. Although sometimes biceps development lags behind for the simple reason that they are not being trained hard enough, nor are they training the biceps with enough different exercises.
To correct specific weak points in your biceps training, the following exercises should be done:
For Mass: You should do heavy barbell curls and cheat curls. Muscle size comes from lifting heavy weights. If you can curl 60 pounds and you train to the point where you can curl 80 pounds, your biceps are going to grow. Its as simple as that!
For Length and Lower Thickness: Curls that concentrate on the lower third of the range of motion. Strict movements, like preacher curls, one of my favorites or incline or prone curls to stretch the biceps to their maximum.
For Height: concentration curls with a dumbbell or cable. Flex the biceps as hard as possible at the top of the movement and do a series of contractions and relaxation. Keep going until you get a tremendous pump. Include burns in your workout, finishing off by bringing up the weight and fully contracting the biceps, then bringing the weight a third of the way, then back up to another full contraction.
For Outside Biceps: Curls done inward toward the center of the body such as narrow-grip barbell curls or narrow-grip preacher bench curls. Concentration curls that bring the weight into your chest. Hold dumbbells in a hammer position-palm turned toward the inside rather than facing upward. Doing this you will feel how this exercise forces the outside of the biceps to do more of the work.
For Inner Biceps: Standing barbell curls, barbell preacher curls done with a wide grip. Seated or standing dumbbell curls, incline dumbbell curls. Standing alternate dumbbell curls in which your arms are kept wide, outside the line of the shoulder biceps. Doing this you will feel it in your inner biceps and they will grow!
In conclusion, I know how it feels to not see your biceps growing the way you think they should or want them to grow. But if you employ these techniques you can be sure that you will overcome your weak points in your biceps training and be on your way to great looking biceps and arm muscles!