Yes, this is true i haven't seen back any back exercises in there. By not doing back and having a strong chest you are going to get a severe imbalance which will make you injury prone. Also, the back muscles are huge muscles...if you're trying to get big i don't know why you wouldn't want to bulk up these awsome muscles.

also, how do you know you're overtraining your muscles? do you hit severe fatigue later on with muscle atrophy? because that's over training. If you're just sore the next day or even for a few days that isn't over training, that is optimal training. You should feel those muscles loud and clear the next day and be slightly sore for a few days. I don't think i would come close to getting the gains i wanted with 2 exercises. I do 3 exercises at the least. Hell, you're only hitting that muscle group 1 time a week. If you're hitting it 3 times a week then i could see reducing the exercises but 1 time a week, blow them out! you have 7 full days of recovery. People are too scared of overtraining and in turn don't train hard enough and wonder why they aren't getting good gains. During my build phases of 6 weeks at a time, i'm continuously sore. If i don't wake up with a sore muscle group then I feel that i didn't train hard enough. I can sustain this for 6-8 weeks and still have an overall good feeling therefore i'm not over training.

We need to post a huge sticky on what over training really is so people will understand. It's not soreness. It's a whole body problem when you get fatigued and can't function normal. That doesn't happen after 1 workout. It happens after training too hard for multiple weeks on end. When you are on a cycle, it's even harder to over train because your body will repair faster. On cycles i train twice a day.