The leaders are different lengths because they are different distances from the needle. To anyone making leaders, I strongly suggest you prewash/shrink the canvas, because if you later need to spot clean the leaders, they won't spot shrink and wrinkle. Ask me how I know... I had to completely remove my leaders, wash, dry, iron, iron, iron, and reattach them. And now they are significantly shorter (left to right, along the poles) then they should be. Canvas shrinks ALOT.