How to Squat: ATG or Parallel?

   Today as it's 7 in the morning, and I already finished my leg workout and drank my first shake for the day, I realized I haven't posted anything in a while! I decided since I have the ENTIRE day to do whatever I want (which NEVER happens, by the way), I wanted to tackle an issue that becomes a "great debate" among bodybuilders and weight lifters alike: Should you go ATG (Ass To Grass), or just parallel when you do your squats? The CORRECT answer varies on a few degrees, here they are.
   When I did squats today, I decided to try something different, and go below parallel. Reaching the bottom was exciting, but I had a slight issue: my right knee started to HURT. As carefully as I could, I raised myself back up without hurting myself any more than I did going down. Relieved, I continued to only go to parallel. Why was this the smartest decision I made? I LISTENED TO MY BODY! Sorry to shout that out, but it's VERY important to do that, and people tend to neglect that. They just want to load up the weight, do what everyone tells them, and risk needing surgery in the later months of training.
   Your body is the greatest indicator of what's going to work for you, and what's not. If it hurts, your body is telling you to STOP! People that have only begun to train don't quite know this yet, and that's why I feel it's important to get a trainer the first six months of your training for this fact alone (later on, it's equally important to use a trainer, but for different reasons). A smart trainer is someone that will make sure you take things slowly, and you don't try to "ego lift" and risk injury in the beginning stages of your training. Someone that's done this for YEARS will know when the body is mad at them for pushing too hard, and they have a better feel of what works for them.
   On top of your body telling you to stop, there's other ways to determine if you should use parallel or ATG. People with shorter legs tend to get away with using ATG more, since the ROM (or Range of Motion) is about equal to say, someone with longer legs only going parallel. I have longer legs than the normal sized man, so I only need to go to parallel to hit the same muscle groups as hard as the shorter man that goes ATG.
   I also do things people say you shouldn't do, such as hack squats, or squats where the bottom of the rep is sitting on a bench, and slowly raising myself up. Doing these squats are helpful to finish off the quads when you can't do full-range squats anymore, and even the Great Austrian Oak used the same techniques. The point of bodybuilding is to push your body to complete failure so it can re-build itself back up again. Using these tactics as well as cheat reps can help you build mass (don't use ONLY cheat reps, be sure to use lighter weights with good form shortly after the cheat reps as well to reinforce proper muscle teardown and to avoid injury).
   So in summary, people are going to tell you it's either one or the other. I say, however, to listen to what your body tells you, and stick to what works best for your body. Remember: it's YOUR body to build, not OTHERS to destroy.