One of the things I, and most other spinners, strive for in spinning is consistency. I’m pretty good at it. Proof: each of these bobbins once held about 220 yards. When I finished plying them together, this is how much was leftover:
The yarn I was making was navy blue. The other colors you see are the leader yarns, which remain on the bobbins permanently.
The bobbin on the left emptied first. The middle one had perhaps 6 inches left on it, and the one on the right about 1.5 feet. I wind up with this much fairly regularly. On the rare occasions I wind up with more left over, it’s usually because I didn’t divide the fiber evenly enough.
(Yes, I’m bragging a little. But it is a pretty impressive skill to have, so I think I’ve earned it!)