michealA soreness will go away easier with a fbw than a split because you are training the specific sore muscle more often.
and as far as faliure is concerned for strength or hypertrophy it has been general knowledge for many years that faliure is not needed.
here is a quote from bryan haycock HST site
Further discussion on fatigue and its relation to a proper hypertrophic stimulus
The 1st set, as with the 2nd set, merely places a given amount of strain on the tissue. As long as you are supporting the weight, the stimulus is present.
You may have heard some discussion about fatiguing fibers becoming disassociated from the rest of the contracting fibers, and thus avoiding the strain. This is true in one sense, and false in another. As a fiber fatigues, it is true that it will stop contracting. When enough fibers fatigue, the tissue as a whole will no longer be able to move against the resistance and you have reached what we call “momentary muscle failure”. Some studies done using eccentric exercise have demonstrated that high resistance eccentric reps produce more microtrauma when done by a fresh muscle, when compared to eccentric reps done after pre-fatiguing the muscle. This would not be wholly unexpected given the above explanation about fatiguing fibers.
However, there is another issue involved that must be taken into account. No fiber is completely isolated from the rest of the tissue, even when it becomes fatigued. So even when one fiber becomes fatigued (sarcomeres by sarcomeres) that fiber will still experience passive stretch by virtue of being attached to adjacent and in-series fibers. So even if a fiber fatigues right away, if the set continues, that fiber will be stretched and strained with the rest of the tissue, the only difference being that the forces will be shifted from the contractile elements of the fiber to the outer structural elements of the fiber. As we know, both passive and active strain/stretch produce hypertrophy.
In short, fatigue is not a critical factor, although it obviously holds importance given the nature of “lifting” weights.
I think where more confusion comes in, is when people begin talking about "intensity". Intensity is generally associated with effort; the greater the effort required, the greater the intensity. This naturally leads to the idea that the last few reps, which require the most effort, are the most effective. If we are strength training, this is often true. However, when training for muscle growth, the fatigue generated by training to failure and beyond (e.g. forced reps) quickly interferes with our ability to train with sufficient frequency.
i know i cant!