Oooh so that's what that is. I've had it happen numerous times where I was absolutely sure I pressed CTRL+C yet the clipboard was empty. I now use CTRL+X and CTRL+Z just because of that.
It helps because there is visual feedback so you're sure you don't have to go back to the original program and do the copy again. Plus sometimes your original program forgets your selection, with CTRL+X you're sure it's on the clipboard and won't have to return.
But you have found that it helps?