Pretty good discussion guys, this is the stuff we like to see here.
Some of my feelings:
1) Training body part once a week- Depends on your current split. Say for instance my back is lacking, I will train it possibly 3 times in 8 days or some outrageously high frequency.
The once a week thing is pretty bullshit i agree. However, i think for a moderate-advanced trainee doing a non periodization split, you will need at LEAST 4 days to recover from the previous workout (unless you are doing a low volume powerlifting split like Westside): a typical split that is high frequency will look like:
1) chest/back
2) legs
3) rest
4) arms, shoulders
5) rest
6)repeat
2) Training to failure- one of my favorite topics!
I know what most of T-Nation says, and they are an awesome site, but i have set to see once where they used a word describing CNS fatigue other that "fry" or "taxing". That doesnt cut it. A "fried" CNS is called the Central Fatigue Hypothesis. To quote Dr. Samuels:
"It is believed that central fatigue is the result of numerous physiological changes including decreased glycogen stores, decreased branched-chain amino acid (BCAA) concentrations, and increased blood levels of free fatty acids (FFA), free tryptophan (fTryp), and serotonin (tryptophan is the precursor to serotonin)."
fTryp and BCAA's compete for absorption through the blood brain barrier, where fTryp is able to do this much faster, causing the increase in serotonin. Increased serotonin is the reason for inhibited CNS efficiceny. Because BCAA's become depleted during weight training, the fTryp levels are much higher than BCAA's, therefore fTryp is much more easily absorbed, by supplementing with BCAA's, the ratio of fTryp/BCAA will be equalized more, thus preventing the absorption of fTryp in the brain is not as efficient.
edit: Just wanted to point out that tryphtophan levels are really high in turkey, which is the reason you feel so lethargic after eating turkey.
Now that we know what CNS overstimulation is, we know how to easily prevent Central Fatigue, eat your ass off, and supplement with a good whey protein or BCAA's and this should not be a problem.
Training to failure is far superior than stopping a rep or two short. You may often hear the term "all or none" refering to muscle contractions, meaning the muscle either contracts or it doesnt, this is false. During a muscle contraction, you do not recruit all muscle fibers and motor units possible. However, by training to failure, you achieve what is known as full Motor Unit Activation. This means you break down as much of the muscle fiber (specifically do damage to the contractile protein, actin and myosin), which means it will build up bigger and stronger. Failure training also allows better Motor Unit syncronization, where the motor units all fire together in a more efficient pattern. | 
