And therein lies one of the biggest problems I see these days concerning training; over complication. Seriously, when did one need to be a quantum physicist to be able to build some muscle?
You quoted CW's "30 Day Mass Plan" article, yet the above question seems to suggest that you didn't read the entire article. The answer to that question is in the article itself.
Don't make the mistake that it seems like a lot of people around here are making lately, "paralysis by analysis". Building muscle isn't as complicated as it is often made out to be.
Here, I'm going to give you a simple formula for building muscle. You can plug this formula into any program that you want (full body, splits, low frequency, high frequency, low intensity, high intensity, etc...). And, if any program is lacking in the following equation it will produce suboptimal results (at best).
Building muscle = Progressive overload + Caloric Surplus + Adequate Rest and Recovery
Progressive overload means lifting more weight or the same weight for more reps each and every time you hit the gym (for the same exercise). If you're not beating your last performance, then your body doesn't have any reason to supercompensate (build muscle). I don't care how much you confuse the muscle, or how many different rep ranges you use, or whatever.
Caloric surplus means that if you're not eating enough to allow for mass gains, no program in the world is going to be some sort of magic bullet that will get you to your goals. Diet is especially key for "naturally" ectomorphic individuals. In other words, if you've "always been lean, but small" then you'd better believe that the primary problem is most likely your diet, not your training.
Adequate rest and recovery should be pretty self explanatory, but I'll touch on them briefly anyhow. Now, this is one area where you see a lot of conflicting ideas. Some people (like CW) suggest that one not allow for complete recovery and try to build up cumulative fatigue. Then once an adequate amount of cumulative fatigue has been accumulated, one should rest completely and allow for complete recovery (which hopefully will lead to a supercompensation effect).
Other people will suggest that you shouldn't train the same muscle again until complete recovery and supercompensation have occurred. The definition of recovery that CW suggested you "thumb your now at" is the same one supported by this group.
The thing is, there have been many more people through out history that have followed the second approach and achieved noteworthy physiques than there have been who followed the "planned overtraining" approach that CW supports. Does that mean that one is necessarily better than the other? No. It just means that one is more time tested and proven.
In the end which ever you choose just make sure that you apply the formula that I stated above. This may however cause you to realize that one approach is better than the other FOR YOU. I capitalized that for a reason. Bodybuilding/building muscle is an individual activity, and due to this different people will respond differently to the same program. Finding out what you respond best to can be a bit of a challenge, but it's also necessary.
Hope this helps.