Once a minute, eh? In all reality, trying it that often would probobly corrupt your data. A rule of thumb is to defragment your hard drive once a month, adjusting to how much you use it. The more you use it, the more often it should be defragmented.
Ah-ha! Guards, arrest him!
"..."
Well, what are you waiting for?!
"We're on break!"
Fine, I'll do it myself!
*trips over a rock and lands in a pit of venomous mulch*