An article on Slashdot about the failure of a Space tether experiment had a very interesting comment. The comment author mentions how difficult it is to wind spools of any length. He mentions a discussion on spool winding, and companies specializing in spool winding.
Two other experiences attest to the difficulty of this problem:
Fishing reel spool
Anyone who used a cheap $10 fishing rod and reel can attest to how frustrating it is when the reel does not wind the fishing line well. Your casts will be short, and you will spend a lot of time untangling the cheap line.
Knitwear yarn must be pre-processed and spooled on cones before it can be fed to knitting machines. This requires special machines to give the yarn the correct tension and eliminate the knots in it. The width of the yarn on the processed cone is many times more the cone's diameter. If a cone with yarn on it gets unwound, it is an unsalvagable mess.