Then there is the "Go for the burn" people who will try to convince you that the pain you get from the slow reps is necessary for growth. Here is what I have to say about that "bullshit." Muscles are made and designed for speed. You don't see people walking around at .00001mph. The faster you can move the weight through space, the more stress is applied to the muscle. That is the exact opposite of what slow trainers are saying.
And as for the burning sensation that you get when you do super-slow reps, that is from a buildup of lactic acid in the muscles and not from any increased stress. The two things that stimulate your muscles are the weight and the speed of the muscle contraction. When you do slow reps, you must use less weight than normal and keep yourself from contracting too fast. In essence you are doing the exact opposite of what you should be doing for maximum muscle growth.
The only problem with training at maximum speed is that the momentum created can lead to sloppy from, risking injury. Also, if the speed of the repetition is too fast, it can reduce the stress to the muscle by relying on more momentum.
That is why the best approach to an exercise is to perform each repetition fast as possible while still maintaining proper form and constant control of the weight. This will produce maximum stress while minimizing the chance of injury.
The same goes for any body parts you exercise. Any longer than 3 days between workouts and you will risk atrophy. On the other hand, it is important to remember that just because atrophy begins 72 hours after a muscle has been stressed does not mean that it takes 72 hours for recovery. Contrary to what some may claim, a muscle recovers much faster than it begins to atrophy.
Likewise, sorness is no indicator of proper recovery. Sore or not, a muscle can be trained five hours after previous training. Along this line, it must be said that the old bodybuilder tale that you can only train a bodypart twice a week for growth and three times a week for definition is way off the mark. This is simply another one of those dumb beliefs that got perpetuated and handed down over the years.
I have found that with the use of supplements and proper training porcedures, and training the same body parts three times daily, six days a week I've achieved awsome results. It is certainly no problem to train a body part daily and make progress as long as you know your limit to acute and chronic overtraining. I usually go all the way until I just barely reach chronic overtraining and just stop for 2-4 days and start right back up again.