Fly, take the top loop apart, straighten out the bundles the full length and start at say 9".
Personally, for large loops like on a recurve, 7.5 seems a little short for top limb!
The jig is not universal when it comes to finished lengths. Keep notes, and keep consistent in your lengths.
We all twist a bit different! As your loops become tighter, and uniform with practice, you should experience shorter lengths, and less stretch in your strings. No matter whether dacron or hp materials.