"If jumping off a small plyo box helps my vertical leap, then jumping off a building will help that much more."
Whenever I think about this, I'm reminded of my uncle who survived a fall of 39 stories off a building. Unfortunately, the building was 40 stories. Get it? He was fine for 39 stories; it was the last one that did him in. Of course, my uncle was an optimist. At the 26th floor a lady leaned out the window and asked, "How's it going?" My uncle answered, "So far, so good!"
Okay, sorry, enough of that.
This little warning illustrated by the statement above is perhaps the most ignored in most people's training programs.
"If two sets of curls make my biceps pump, I'll do twenty and the pump will stay with me until the lights come on at the club at three in the morning."
Well, the pump doesn't last that long and what are you doing at a club that late anyway? Basically, I'm talking about overkill here. You shoot the deer, then pump it full of twenty more shots "just to make sure." It's the most common error in sports:
You've seen it. You've done it. We all do it. Stop doing it.