My friend Al Perryman use to do this years ago. He would tie up dozens of mid-sections for big game leaders and then loop them together and wind them up on an empty line spool.

He would have a heavy butt section already on his fly line with a perfection loop.

He then would un-loop a class section with 100% Bimi-twist knots on both ends and loop it to his butt section.

Then he would Albright or Huffnagle on his shock tippet and tie on a fly.

Now the Cam Sigler company has these sections pre-tie on a spool for $36USD dozen. They come in 12#, 16# and 20# IGFA sizes.

We just ordered them this week and should have then soon.