In making the thread, i intended the term 'shocking' the muscle in the context of changing exercises and set/rep schemes, not in taking a layoff or break or deconditioning.
I too have always thought it was BS, but i can't be sure.
To my mind, the muscle doesn't know whether your lifting a bag of rocks or a dumbell, only the stress applied to it.
If that's the case, assuming compound exercises are the most stressful to complete, doesn't it stand to reason that those exercises will achieve most growth. So then why replace them for the sake of replacing them with less 'stressful' exercises, for lack of a better term, simply to 'shock' the muscle.
The only doubt i have in my mind is the effect that a shock exercise can have on muscle soreness the next day. Why is it that muscle often becomes more sore when a new exercises is introduced into a routine?