I found out, to my cost, many years ago that A4 card is allowed to be up to 1mm out in the cut. When you are printing cards for charity and putting 2 A6 cards to an A4 sheet it proves really difficult, especially if the front of the card has a frame.

Now I measure and trim my card accordingly which is such a pain but sometimes you can just look at the card and see where it runs out.

Don't get me started on trimmers though!