QS, look at it this way: when you have a legs day you might go into the gym and do, including warmups, 10 sets of squats. You'll then hit the leg press for another 5 sets. After that, to squeeze the last bit out of the legs, you might move on to do some leg-extensions. All in all, maybe 20 - 25 sets for legs of assorted exercises, maybe more, many taken to failure, depending on the individual.
In BiggT's template above, he'd have JK doing 14 sets split through the week, likely none of which would go to failure at this stage.
It's not sound to make the statement that 3x per week will lead to overtraining. Before we dismiss the Oly lifters who, as you say, on most of their lifts perform only the concentric part of their workout. This doesn't apply to their squatting on which they have to go down and then come back up just like anyone else.
I'm not suggesting that 1x per week will not work well for any trainee if it's performed with progression as a goal but many, many studies on athletes have shown that 2x or 3x is better than 1x per week. It certainly leads to better conditioning and, as I mentioned previously, reduces needless muscle aches.
At it's simplest, imagine the squatting he'd do in one workout spread over three workouts. How can anyone suggest that this is more likely to lead to overtraining than performing all of the work in one workout? Almost any long-term program is down to manipulating the variables of Intensity (%-age of 1RM), Volume (sets / reps per workout) and frequency (how often one works a lift). By manipulating these variables, stress and any tendency to overtrain can be controlled.
With dual-factor training, for the more advanced trainee, the variables are set to head for overtraining deliberately. As it approaches, and the trainee gets into over-reaching and starts to feel his performance fall, the variables are reduced and modified to permit recovery and ongoing gains before cycling again in a wave-like manner. There are many variations.
For anyone interested in learning more, I can recommend spending some time at
Madcow's Geocities site
Athletes have been using these principles for decades. They were the principles that lead the Soviets to dominate the lifting stage and allowed the US to compete on even terms again afterwards. These principles work both for muscular gains and for performance whether training naturally or on gear.