Mistakes

There is a quote that JD from Scrubs says that I just can't get out of my head: "Even if you've done a procedure five thousand times, there's no guarantee you won't screw up number five thousand, one."

So what is it that makes us mess up what is most likely second nature to us? We have done things so many times before, so what makes this time different? Do we never truly master anything? Or are we simply distracted that five thousand, first time?

They say that practice makes perfect, but what makes that four thousand nine hundred and ninety nineth time so different to the five thousand, first? What is it that distracts us?

So can we stop ourselves from repeating the mistakes we make? Does practice ever really stop us from making them? Or does life work on ratios? 5000:1 right to wrong? But generally the odds are substantially lower, at least that is what I've found...or is that just me?