I was cutting all the peices for a production run of 4 W10's recently. I would cut four of the same piece, set them aside to the right grab from the left, cut four pieces set them to the right.
It was getting late and as I cut four squares from these "left over" rectangles on the last one I realized they were panels I had already made

Of course they had double bevels and all that.
The worst part was that as I was cutting the last one, I realized what I was doing and looked over where I had grabbed the pieces from. Took my eyes off the table saw

the piece bound in the saw and shot me 3 inches above my twig and giggle berries hard enough to hit me fly five feet and knock over some other wood. This is how I looked for a few minutes
Never, never stop paying attention to your tool! (and don't work until after 12am if you can help it)
Benj