So have you actually owned a box-fresh leather and worn it to the point where creases develop on the sleeves, or is your opinion based on your experience with cotton and wool? I'm not familiar with your closet, but the sleeves on my lamb jackets have eventually settled a bit higher than they did out of the box. My CWU-45, despite arriving with the same measurements as my A2, now has sleeves that are noticeably shorter when they're hung together. I wear my CWU-45 the most, and my A2 the least.
I'm not saying that it'll bring this stuff to wrist level or anything, but I don't think that should be the ideal anyways.
Yeah, I have owned both lamb and calf before. I can attest to lamb being almost negligible in terms of shrinkage. Calf shrinkage seems like a little more. But honestly who cares? I'm not pedantic enough to calculate fractional inch loss in sleeve shrinkage pre and post wearing for a leather jacket. That's insanity.
If it hits the wrists, it fits. I don't think Sid Vicious or Marlon Brando preemptively accounted for sleeve accordions or took a tape measure out to compare shrinkage over time.