I used to think numbers as high as quadrillion were made up merely for the sake of convention, since its nearly impossible to quantify anything at a non-microscopic level in the quadrillions...and lets face it, microscopic level quantities are better suited for expression in scientific notation.
Today we have a reason to use the term, because something quantifiable of importance has just surpassed 1 quadrillion: Japanese debt. I use the word importance with a bit of sarcasm, because at this level the currency's demise is a foregone conclusion and an increase in the number of 0's is hardly important. The worst part is that the farce has life; this has not been and will not be a fast meltdown. It's a smoked brisket, which can get infinitely more tender until someone decides that its time to take it off the grill.
That all being said I have no doubt I will be long USD/JPY again... although I feel no rush to enter the trade as this will be a long, dreadful, winding road which I am sure will present many opportunities along the way.