There are MANY chains, with MANY lengths of links, diameters, etc. To talk of chain as it is one standardized commodity is erroneous. I have seen chains with short fat links, and chains with long lean links, and then I have seen chains with long fat links. And then I have seen anchor chains with a crossmember that take shackles out of the equation, except as used ONLY on the end. Chain has many types.
Steve