I might be in the minority but I am of the opinion when you are trying to make your body stronger so do the exercise in the hardest way not they easiest way. Using a wide grip and only chinning to your chin is shortening the range of motion. Also not using the negative by dropping quick is doing half reps. In the same vein has anyone seen cross fit pullups. They are called kips and they jerking you body up in a circular pattern. People who develop the skill can knock out 40 plus of them without breaking a sweat but they are not pullups. They are kips.
Doing pullups you should concentrate on pulling your elbows as low as they can for complete contraction. You will get very few reps doing pullups correctly but you're there to target muscles and not to impress others with the rep count.
