Sorry Doc, I should've qualified that last sentence! I just didn't want to make it too long!
I think the key is to hit the wall and recover. Depending on other factors, such as age, activity, diet and most importantly how much stress is in your life at the time, how long it'll take to recover will vary. So, as I think of it, you've got 3 things that could happen:
You push your limits so far your CNS does not recover. This would result in an actual physical disease or syndrome such as chronic fatigue.
You hit the wall, but the time and adjustments needed to recover result in either a loss in size/strength or less gains than if you did not reach that stage and continued training.
You hit the wall, and you recover greater size/strength by recuperating than you would have gained from training normally in the recovery phase.
I think that 1. can only occur with world class athletes. It is very very rare to see someone who is so gifted physically and mentally that they can continue work at the very limits of their bodies abilities without getting injured for the time required for this to happen.
Whether 2. or 3. happens I think depends on the factors in your life, like stress and nutrition, in conjunction with how far you've gone past your CNS "threshold". Too little elicits too little gains, too much involves too long a recovery. It's all about the point of diminishing returns, and I think that recognising that point for an individual and how to use it to their benefit is what makes great athletes in any sport.
It makes great coaches too, but it is much rarer for a coach than an athlete, because an athlete has their own body letting them know. It's easy for an experienced athlete to "instinctively" know when it's time to back off if they've pushed their limits too far or too often.
Anyhow, hope that explains what I meant previously. I experience my symptoms, have a lighter training week, and come back bigger better. Obviously I'm going to keep doing what I'm doing until it ceases to work! If I had to take longer to recover, then it would start becoming a matter of diminishing returns and tweaking things until it works.
P.S Keep up the good work Doc, I saw your 4 month progress vid on your log. It'd be great to see where you are after a year!