Well first off, what do you mean by "shocking" a muscle? Muscles cannot differentiate between exercises, they contract or they don't. Yes the nervous system can (not really, but you know) by altering recruitement patterns in order to optimize itself to a given movement. So, I guess you mean by "shock" you mean change the nervous systems recuitment patterns. When you do this, you take a step back in your quest for muscle growth because the nervous system has to start the "learning" period all over again. It takes 4-6 weeks for this period to complete (the more cimplcated the lift the longer this takes), and you can't maximally stimulate a muscle until AFTER this process is over with.
So, by trying to "shock" your muscles you are actually just taking a step back in trying to gain muscle...and besides, the whole technique sucks because it's entirely based on feeling the "burn".