It's very easy to lose track of which piece came from which piece of veneer. I mark my individual sheets to help me keep them oriented and tied together. In the picture above, the two pieces came from sheet number 3 and sheet number 4 (top corners are marked). Although you would think as long as these two pieces stayed together, it wouldn't matter which side was up and which side was down. There's a definite difference in the character of the wood when flipped over and it doesn't line up as well one way vs the other. Picture on the right is the same two pieces as on the left but flipped over to see the back side

tiny | small | medium | large | xlarge | huge